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Yoschenko V, Nanba K, Wada T, Johnson TE, Zhang J, Workman D, Nagata H. Late phase radiocesium dynamics in Fukushima forests post deposition. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2022; 251-252:106947. [PMID: 35732077 DOI: 10.1016/j.jenvrad.2022.106947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 06/14/2022] [Accepted: 06/14/2022] [Indexed: 06/15/2023]
Abstract
The long term dynamics of radiocesium in typical forest ecosystems was studied in the radioactive contaminated areas in Fukushima Prefecture. Six observations sites located in Yamakiya Village (Kawamata Town; since 2014), Tsushima Village (Namie Town, since 2015), and Tomioka Town (since 2017) were monitored. The forests consisted of artificial plantations of Japanese cedar (Cryptomeria japonica) at Yamakiya Village, Tsushima Village, and Tomioka Town. Tsushima Village also had a natural mixed forest dominated by Japanese red pine (Pinus densiflora), and Tomioka Town had a young and a mature artificial plantation of Japanese cypress (Chamaecyparis obtuse). Concentrations of 137Cs were monitored in the samples collected from the main aboveground biomass compartments, fresh litterfall, forest litter, and soil. Concentrations of exchangeable forms of 137Cs and stable K were measured in soil samples. During the observation period, the litter radiocesium inventories at all sites decreased significantly to approximately 1% or less of the total ground deposition. Approximately 80% of the total radiocesium inventory is localized in the upper 5-cm layer of soil and there is little downward migration of radiocesium. At the sites with the longest monitoring series (Yamakiya and Tsushima), the radiocesium expectation depths and expectation mass depths were relatively constant at 2-3 cm and 5-6 kg m-2, respectively. Aboveground biomass compartments showed similar decreasing trends in radiocesium aggregated transfer factors, Tag, in the compartments that were exposed to atmospheric fallout in March 2011 (old foliage, small branches, and outer bark). The mean Tag in cedar stand compartments currently are in the range of 10-3-10-2 m2 kg-1 dw. However, the mean Tag and their dynamic trend significantly differed in the wood compartments of the cedar stands, which may indicate root uptake differences of orders of magnitude between observation sites. The difference in radiocesium concentration in wood between the sites becomes less pronounced when normalized by the ratio of exchangeable 137Cs/K in the soils.
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Affiliation(s)
- Vasyl Yoschenko
- Institute of Environmental Radioactivity at Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan.
| | - Kenji Nanba
- Institute of Environmental Radioactivity at Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
| | - Toshihiro Wada
- Institute of Environmental Radioactivity at Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
| | - Thomas E Johnson
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, 80523, United States
| | - Jian Zhang
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, 80523, United States
| | - Daniel Workman
- Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO, 80523, United States
| | - Hiroko Nagata
- Institute of Environmental Radioactivity at Fukushima University, 1 Kanayagawa, Fukushima, Fukushima Prefecture, 960-1296, Japan
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Decadal trends in 137Cs concentrations in the bark and wood of trees contaminated by the Fukushima nuclear accident. Sci Rep 2022; 12:11243. [PMID: 35788621 PMCID: PMC9253084 DOI: 10.1038/s41598-022-14576-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 06/09/2022] [Indexed: 11/13/2022] Open
Abstract
Understanding the actual situation of radiocesium (137Cs) contamination of trees caused by the Fukushima nuclear accident is essential for predicting the future contamination of wood. Particularly important is determining whether the 137Cs dynamics within forests and trees have reached apparent steady state. We conducted a monitoring survey of four major tree species (Japanese cedar, Japanese cypress, konara oak, and Japanese red pine) at multiple sites. Using a dynamic linear model, we analyzed the temporal trends in 137Cs activity concentrations in the bark (whole), outer bark, inner bark, wood (whole), sapwood, and heartwood during the 2011–2020 period. The activity concentrations were decay-corrected to September 1, 2020, to exclude the decrease due to the radioactive decay. The 137Cs concentrations in the whole and outer bark samples showed an exponential decrease in most plots but a flat trend in one plot, where 137Cs root uptake is considered to be high. The 137Cs concentration ratio (CR) of inner bark/sapwood showed a flat trend but the CR of heartwood/sapwood increased in many plots, indicating that the 137Cs dynamics reached apparent steady state within one year in the biologically active parts (inner bark and sapwood) and after several to more than 10 years in the inactive part (heartwood). The 137Cs concentration in the whole wood showed an increasing trend in six plots. In four of these plots, the increasing trend shifted to a flat or decreasing trend. Overall, the results show that the 137Cs dynamics within forests and trees have reached apparent steady state in many plots, although the amount of 137Cs root uptake in some plots is possibly still increasing 10 years after the accident. Clarifying the mechanisms and key factors determining the amount of 137Cs root uptake will be crucial for predicting wood contamination.
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Ota M, Koarashi J. Contamination processes of tree components in Japanese forest ecosystems affected by the Fukushima Daiichi Nuclear Power Plant accident 137Cs fallout. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 816:151587. [PMID: 34838924 DOI: 10.1016/j.scitotenv.2021.151587] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 10/30/2021] [Accepted: 11/06/2021] [Indexed: 06/13/2023]
Abstract
In forests affected by the Fukushima Daiichi Nuclear Power Plant accident, trees became contaminated with 137Cs. However, 137Cs transfer processes determining tree contamination (particularly for stem wood, a prominent commercial resource) remain insufficiently understood. We propose a model for simulating dynamic behavior of 137Cs in a forest tree-litter-soil system and applied it to contaminated forests of cedar plantation and natural oak stand in Fukushima to elucidate relative impact of distinct 137Cs transfer processes determining the tree contamination. The transfer of 137Cs to the trees occurred mostly (>99%) through surface uptake of 137Cs trapped by needles and bark during the fallout. Root uptake of soil 137Cs was several orders of magnitude lower than the surface uptake over a 50-year period following the accident. As a result, internal contamination of the trees proceeded through an enduring recycling (translocation) of 137Cs absorbed on the tree surface. A significant surface uptake of 137Cs through bark was suggested, contributing to 100% (leafless oak tree) and 30% (foliated cedar tree; the remaining uptake occurred at needles) of the total uptake by the trees, although that pathway still needs to be evaluated by experimental evidence. It was suggested that the activity concentration of 137Cs in stem wood of the trees at these sites are currently (as of 2021) decreasing by ~3% per year, mainly through radioactive decay of 137Cs and partly through dilution effect from tree growth. Although further refinement of the model is recommended, for example by including tree species specific 137Cs transportation in stem, these findings provide vital information for planning of forestry reactivation in Fukushima; e.g., removal of forest floor organic layer will not reduce the tree contamination for a long term because of the 137Cs absorption via the tree surface substantially greater than root uptake of 137Cs deposited to the floor.
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Affiliation(s)
- Masakazu Ota
- Research Group for Environmental Science, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan.
| | - Jun Koarashi
- Research Group for Environmental Science, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki 319-1195, Japan
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Hashimoto S, Tanaka T, Komatsu M, Gonze MA, Sakashita W, Kurikami H, Nishina K, Ota M, Ohashi S, Calmon P, Coppin F, Imamura N, Hayashi S, Hirai K, Hurtevent P, Koarashi J, Manaka T, Miura S, Shinomiya Y, Shaw G, Thiry Y. Dynamics of radiocaesium within forests in Fukushima-results and analysis of a model inter-comparison. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2021; 238-239:106721. [PMID: 34509097 DOI: 10.1016/j.jenvrad.2021.106721] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 08/09/2021] [Accepted: 08/13/2021] [Indexed: 06/13/2023]
Abstract
Forests cover approximately 70% of the area contaminated by the Fukushima Daiichi Nuclear Power Plant accident in 2011. Following this severe contamination event, radiocaesium (137Cs) is anticipated to circulate within these forest ecosystems for several decades. Since the accident, a number of models have been constructed to evaluate the past and future dynamics of 137Cs in these forests. To explore the performance and uncertainties of these models we conducted a model inter-comparison exercise using Fukushima data. The main scenario addressed an evergreen needleleaf forest (cedar/cypress), which is the most common and commercially important forest type in Japan. We also tested the models with two forest management scenarios (decontamination by removal of soil surface litter and forest regeneration) and, furthermore, a deciduous broadleaf forest (konara oak) scenario as a preliminary modelling study of this type of forest. After appropriate calibration, the models reproduced the observed data reliably and the ranges of calculated trajectories were narrow in the early phase after the fallout. Successful model performances in the early phase were probably attributable to the availability of comprehensive data characterizing radiocaesium partitioning in the early phase. However, the envelope of the calculated model end points enlarged in long-term simulations over 50 years after the fallout. It is essential to continue repetitive verification/validation processes using decadal data for various forest types to improve the models and to update the forecasting capacity of the models.
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Affiliation(s)
- Shoji Hashimoto
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan; Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Taku Tanaka
- EDF R&D, LNHE, 6 Quai Watier, 78400, Chatou, France.
| | - Masabumi Komatsu
- Department of Mushroom Science and Forest Microbiology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan; Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Marc-André Gonze
- Institute of Radiation Protection and Nuclear Safety, PSE-ENV, CE Cadarache-Bat 153, BP3, 13115, St-Paul-lez-Durance cedex, France
| | - Wataru Sakashita
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan; Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Hiroshi Kurikami
- Fukushima Environmental Research Group, Japan Atomic Energy Agency, 10-2 Fukasaku, Miharu-machi, Tamura-gun, Fukushima, 963-7700, Japan
| | - Kazuya Nishina
- Earth System Division, National Institute for Environmental Studies, Tsukuba, 305-8506, Japan
| | - Masakazu Ota
- Research Group for Environmental Science, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
| | - Shinta Ohashi
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan; Department of Wood Properties and Processing, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Philippe Calmon
- Institute of Radiation Protection and Nuclear Safety, PSE-ENV, CE Cadarache-Bat 153, BP3, 13115, St-Paul-lez-Durance cedex, France
| | - Frederic Coppin
- Institute of Radiation Protection and Nuclear Safety, PSE-ENV, CE Cadarache-Bat 153, BP3, 13115, St-Paul-lez-Durance cedex, France
| | - Naohiro Imamura
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Seiji Hayashi
- Fukushima Regional Collaborative Research Center, National Institute for Environmental Studies,10-2 Fukasaku, Miharu, Fukushima, 963-7700, Japan
| | - Keizo Hirai
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Pierre Hurtevent
- Institute of Radiation Protection and Nuclear Safety, PSE-ENV, CE Cadarache-Bat 153, BP3, 13115, St-Paul-lez-Durance cedex, France
| | - Jun Koarashi
- Research Group for Environmental Science, Japan Atomic Energy Agency, 2-4 Shirakata, Tokai, Ibaraki, 319-1195, Japan
| | - Takuya Manaka
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Satoru Miura
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Yoshiki Shinomiya
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - George Shaw
- School of Biosciences, University of Nottingham, Sutton Bonington, LE12 5RD, UK
| | - Yves Thiry
- Andra, Research and Development Division, 1-7 Rue Jean-Monnet, 92298, Châtenay-Malabry cedex, France
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Sotiropoulou M, Mavrokefalou G, Florou H, Kritidis P. Determination and mapping of the spatial distribution of cesium-137 in the terrestrial environment of Greece, over a period of 28 years (1998 to 2015). ENVIRONMENTAL MONITORING AND ASSESSMENT 2021; 193:591. [PMID: 34420128 DOI: 10.1007/s10661-021-09325-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Accepted: 07/17/2021] [Indexed: 06/13/2023]
Abstract
In this study, we are applying the GIS techniques in order to record the data that have been collected for cesium-137, over the for the period 1998 to 2015, for the terrestrial environment in Greece. Following the Chernobyl Nuclear Power Plant (CNPP) accident in 1986, extended fieldwork was conducted for the determination of cesium-137 concentrations in the terrestrial environment. In 2011, in the light of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, new campaigns were organized in order to assess the variation in cesium-137 activity concentrations. The measured data, combined with data taken from the databases of the Environmental Radioactivity Laboratory (NCSR'Demokritos', in Athens, Greece), as well as, from the European Atlas of Cesium Deposition on Europe, are being used for the spatial distribution analysis of cesium-137 in the country. Furthermore, are used for the temporal analysis of this radionuclide in a long-term basis. Moreover, we are using the ERICA Assessment Tool for the calculation of the dose rate that the studied organisms (plants of Poaceae spp. and mammals of Bovidae spp.) receive due to the exposure to cesium-137. All gathered information provides us with thematic maps, designed through the GIS techniques, that allow for an appropriate representation of cesium-137 presence in the country nowadays. This study provides an insightful view of the behavior of this anthropogenic radionuclide that is useful for future research in order to elucidate its behavior in long-term periods. The knowledge of the environmental fate of radionuclides is important because it contributes to the projection of long-term risks resulting from radionuclide releases, as well as, for the selection of cost-effective remediation strategies. Furthermore, it provides the opportunity to conduct a comprehensive risk assessment in the region, as the studied organisms were exposed to low-level ionizing radiation. But, as it was shown, on the level of ecosystem, no significant impact was estimated. However, regarding the future objectives, further consideration of the exposure levels should be considered while taking also into account the exposure to natural and background radiation and the exposure to spontaneous emission of anthropogenic radionuclides, especially if we want to consider the eventual effects of protracted low-level ionising radiation on the various levels of life's organization.
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Affiliation(s)
- Maria Sotiropoulou
- Environmental Radioactivity Laboratory, I.N.RA.S.T.E.S, National Centre for Scientific Research "Demokritos', Agia Paraskevi, 15310, Attiki, Greece.
| | - Georgia Mavrokefalou
- Environmental Radioactivity Laboratory, I.N.RA.S.T.E.S, National Centre for Scientific Research "Demokritos', Agia Paraskevi, 15310, Attiki, Greece
| | - Heleny Florou
- Environmental Radioactivity Laboratory, I.N.RA.S.T.E.S, National Centre for Scientific Research "Demokritos', Agia Paraskevi, 15310, Attiki, Greece
| | - Panayotis Kritidis
- Environmental Radioactivity Laboratory, I.N.RA.S.T.E.S, National Centre for Scientific Research "Demokritos', Agia Paraskevi, 15310, Attiki, Greece
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6
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Lavrinienko A, Hämäläinen A, Hindström R, Tukalenko E, Boratyński Z, Kivisaari K, Mousseau TA, Watts PC, Mappes T. Comparable response of wild rodent gut microbiome to anthropogenic habitat contamination. Mol Ecol 2021; 30:3485-3499. [PMID: 33955637 DOI: 10.1111/mec.15945] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2020] [Revised: 04/07/2021] [Accepted: 04/29/2021] [Indexed: 12/11/2022]
Abstract
Species identity is thought to dominate over environment in shaping wild rodent gut microbiota, but it remains unknown whether the responses of host gut microbiota to shared anthropogenic habitat impacts are species-specific or if the general gut microbiota response is similar across host species. Here, we compare the influence of exposure to radionuclide contamination on the gut microbiota of four wild mouse species: Apodemus flavicollis, A. sylvaticus, A. speciosus and A. argenteus. Building on the evidence that radiation impacts bank vole (Myodes glareolus) gut microbiota, we hypothesized that radiation exposure has a general impact on rodent gut microbiota. Because we sampled (n = 288) two species pairs of Apodemus mice that occur in sympatry in habitats affected by the Chernobyl and Fukushima nuclear accidents, these comparisons provide an opportunity for a general assessment of the effects of exposure to environmental contamination (radionuclides) on gut microbiota across host phylogeny and geographical areas. In general agreement with our hypothesis, analyses of bacterial 16S rRNA gene sequences revealed that radiation exposure alters the gut microbiota composition and structure in three of the four species of Apodemus mice. The notable lack of an association between the gut microbiota and soil radionuclide contamination in one mouse species from Fukushima (A. argenteus) probably reflects host "radiation escape" through its unique tree-dwelling lifestyle. The finding that host ecology can modulate effects of radiation exposure offers an interesting counterpoint for future analyses into effects of radiation or any other toxic exposure on host and its associated microbiota. Our data show that exposure to radionuclide contamination is linked to comparable gut microbiota responses across multiple species of rodents.
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Affiliation(s)
- Anton Lavrinienko
- Ecology and Genetics, University of Oulu, Oulu, Finland.,Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Anni Hämäläinen
- Ecology and Genetics, University of Oulu, Oulu, Finland.,Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland.,Institute of Environmental Sciences, Jagiellonian University, Kraków, Poland
| | | | - Eugene Tukalenko
- Ecology and Genetics, University of Oulu, Oulu, Finland.,National Research Center for Radiation Medicine of the National Academy of Medical Science, Kyiv, Ukraine
| | - Zbyszek Boratyński
- CIBIO-InBIO Associate Laboratory, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, Portugal
| | - Kati Kivisaari
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Timothy A Mousseau
- Department of Biological Sciences, University of South Carolina, Columbia, SC, USA.,SURA/LASSO/NASA, ISS Utilization and Life Sciences Division, Kennedy Space Center, Cape Canaveral, FL, USA
| | - Phillip C Watts
- Ecology and Genetics, University of Oulu, Oulu, Finland.,Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
| | - Tapio Mappes
- Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland
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Matsuura T. Assessment of potentially reusable edible wild plant and mushroom gathering sites in eastern Fukushima based on external radiation dose. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2021; 227:106465. [PMID: 33271395 DOI: 10.1016/j.jenvrad.2020.106465] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 10/31/2020] [Accepted: 11/15/2020] [Indexed: 06/12/2023]
Abstract
Edible wild plant/mushroom gathering, an essential food acquisition and outdoor recreation activity in rural areas, has declined in the area near the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident in eastern Japan. The present study first evaluated the spatial distribution of potential gathering sites of various edible wild plant/mushroom species before the accident by administering a face-to-face questionnaire survey to local gatherers as well as utilizing the group analytical hierarchy process (AHP) and geographic information systems (GIS). Then, the damage to and future reusability of previous gathering sites were estimated from the perspective of the external radiation dose by overlaying maps of potential gathering sites and the time-series air dose rate (ADR) up to 2050 incorporating different gathering frequency scenarios. The study area is located in Kawauchi village in the eastern Fukushima prefecture, at 12-30 km southwest of FDNPP. The spatial distributions of gathering sites before the accident differed widely among species at the local scale because of their different environmental preferences. In contrast, the temporal variation in the reusability of the gathering sites was notably small among different species. The external radiation dose in the potential gathering sites declined sharply in the early post-accident years and gradually in the later years through the physical decay of radiocesium, i.e., 134Cs and 137Cs, with different half-lives. Moreover, the gathering frequency and heterogeneous distribution of radiocesium substantially affected the temporal variation in reusability for the gathering sites. These results indicate that an early resumption of gathering would be possible by reducing the gathering frequency and avoiding higher ADR areas, whereas it will take a much longer period to resume gathering in areas with higher ADR. Further research is required that considers both internal and external radiation doses in the geospatial context for the restoration and safer use of edible wild plants/mushrooms.
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Affiliation(s)
- Toshiya Matsuura
- Tohoku Research Center, Forestry and Forest Products Research Institute, 92-25 Nabeyashiki, Shimokuriyagawa, Morioka, Iwate, 020-0123, Japan.
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Gonze MA, Calmon P, Hurtevent P, Coppin F. Meta-analysis of radiocesium contamination data in Japanese cedar and cypress forests over the period 2011-2017. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 750:142311. [PMID: 33182179 DOI: 10.1016/j.scitotenv.2020.142311] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 09/07/2020] [Accepted: 09/07/2020] [Indexed: 06/11/2023]
Abstract
Since Fukushima accident, dozens of field studies have been conducted in order to quantify and understand the behaviour of atmospheric radiocesium (137Cs) fallouts in contaminated forests of Fukushima and neighbouring prefectures. In this paper, we carry out a detailed review of data acquired over 2011-2017 in Japanese cedar and cypress plantations, focusing on aerial tree organs, soil layers and tree-to-soil depuration fluxes. To enable comparison and reinforce the consistency between sites, radiological measurements were normalized by the deposit and interpolated onto the same spatio-temporal frame. Despite some (poorly explained) residual variability, we derived a "mean" pattern by log-averaging data among sites. These "mean" results were analysed with the help of a simple mass-balance approach and discussed in the light of post-Fukushima literature. We demonstrated that the activity levels and dynamics in all compartments were consistent and generally well reproduced by the mass balance approach, for values of the interception fraction between 0.7 and 0.85. The analysis indicated that about 5% of the initial deposit remained in the aerial vegetation after 6 years, more than two thirds of intercepted 137Cs being transferred to the soil due to throughfall. The simulations indicated that foliar uptake might have contributed between 40% and 100% to the activity transferred to stem wood. The activity concentration in canopy organs rapidly decreased in the first few months then more slowly, according to an effective half-life of about 1.6 years. The activity level in the organic layer peaked in summer 2011 then decreased according to an effective half-life of 2.2 years. After a rapid increase in 2011, the contamination of mineral horizons continued to increase more slowly, 85% of 137Cs incoming through the organic layer being retained in the 0-5 cm layer according to a mean residence time longer than in the upper layer (7 against 1.5 years).
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Affiliation(s)
- M-A Gonze
- Institute of Radiation Protection and Nuclear Safety, CE Cadarache-Bat 153, BP3, 13115 St-Paul-lez-Durance cedex, France.
| | - P Calmon
- Institute of Radiation Protection and Nuclear Safety, CE Cadarache-Bat 153, BP3, 13115 St-Paul-lez-Durance cedex, France
| | - P Hurtevent
- Institute of Radiation Protection and Nuclear Safety, CE Cadarache-Bat 153, BP3, 13115 St-Paul-lez-Durance cedex, France
| | - F Coppin
- Institute of Radiation Protection and Nuclear Safety, CE Cadarache-Bat 153, BP3, 13115 St-Paul-lez-Durance cedex, France
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Shinomiya Y, Kobayashi M, Tsurita T, Tsuboyama Y, Sawano S, Itoh Y, Ohnuki Y, Shichi K. Discharge of suspended solids and radiocesium into stream water in a forested watershed before and after line thinning with spur road construction. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 225:106418. [PMID: 33038692 DOI: 10.1016/j.jenvrad.2020.106418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 08/29/2020] [Accepted: 09/01/2020] [Indexed: 06/11/2023]
Abstract
In an experimental watershed located around 120 km southwest of the Fukushima Daiichi Nuclear Power Plant with a drainage area of 59.9 ha, suspended solids (SS) and radioactive cesium discharge from a forested headwater catchment were monitored before and after line thinning. The lower slopes in the experimental watershed were covered with plantation conifer trees (Japanese cedar), while the upper slopes were covered with deciduous trees. In 2012, line thinning was carried out at a thinning rate of 35% across 17% of the northeastern part of the watershed and across the remaining part in 2013. Spur roads were constructed along all tributaries without water, and logged trees were dragged and grappled using forestry machinery and transported along these roads to timber yards using forwarder-type forestry vehicles. A V-notch weir and a water level gauge were installed at the watershed outlet and stream water was sampled twice a month during base flow, whereas during flood flow, stream water samples of 1 L were collected every hour using an automatic water sampler. These samples were filtered through 0.5 μm glass fiber filters to measure the SS concentration. SS concentration data was collected for 21 floods before thinning and for 37 floods after thinning. A time-integrated SS sampler was installed in the stream close to the weir and SS samples were collected every two or three months to measure their Cs-137 concentrations. SS concentrations before (from July 2010 to August 2012) and after thinning (from October 2013 to December 2018) were compared, where the maximum SS concentrations before and after thinning were 211 and 790 mg L-1, respectively. It was discovered that some SS concentrations during flood flow were higher after carrying out thinning than before. Some ΣLss values (specific cumulative load of SS in a flood event) also showed the same results as the SS concentrations. Thus, it was clear that SS discharge immediately increases after thinning, but as it increases Cs-137 export is limited. This is related to a change in SS source brought about by the process of thinning, a decrease with time in the Cs-137 concentration in organic solid expected from that in litter, and a regrowth of vegetation on spur roads, protecting them against soil erosion. Therefore, it was concluded that thinning does not drastically increase Cs-137 export from a forested watershed.
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Affiliation(s)
- Yoshiki Shinomiya
- For. and For. Prod. Res. Inst, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan.
| | - Masahiro Kobayashi
- For. and For. Prod. Res. Inst, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Tatsuya Tsurita
- For. and For. Prod. Res. Inst, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Yoshio Tsuboyama
- For. and For. Prod. Res. Inst, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Shinji Sawano
- Hokkaido Research Center, For. and For. Prod. Res. Inst, 7 Hitsujigaoka, Toyohira, Sapporo, Hokkaido, 062-8516, Japan
| | - Yuko Itoh
- For. and For. Prod. Res. Inst, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Yasuhiro Ohnuki
- Tohoku Research Center, For. and For. Prod. Res. Inst., 92-25 Nabeyashiki, Shimokuriyagawa, Morioka, Iwate, 020-0123, Japan
| | - Koji Shichi
- Shikoku Research Center, For. and For. Prod. Res. Inst, 2-915 Asakuranishi, Kochi, Kochi, 780-8077, Japan
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10
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Sakashita W, Miura S, Akama A, Ohashi S, Ikeda S, Saitoh T, Komatsu M, Shinomiya Y, Kaneko S. Assessment of vertical radiocesium transfer in soil via roots. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 222:106369. [PMID: 32801027 DOI: 10.1016/j.jenvrad.2020.106369] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 07/22/2020] [Accepted: 07/22/2020] [Indexed: 06/11/2023]
Abstract
Several years after the Fukushima Daiichi Nuclear Power Plant accident, the surface mineral soil layer is believed to be the main reservoir of radiocesium (137Cs) in forest ecosystems in Japan. Dissolved 137Cs combines with clay minerals in the soil, and hence, it is not expected to easily infiltrate over time. However, previous studies have indicated that 137Cs derived from the older global fallout migrated deeper than that of the Chernobyl accident, and this cannot be explained by only the dissolved 137Cs vertical migration in the soil. Considering the carbon and nutrient dynamics in the forest floor, the 137Cs transfer process in soil via roots may alter its vertical distribution on a decadal scale. Therefore, in this study, we investigated the 137Cs activity concentrations in both roots and soil matrix, by considering four (0-20 cm) or six (0-30 cm) mineral soil layers taken at every 5 cm at seven study sites dominated by one of the six plant species (three coniferous forests, one deciduous forest, two deciduous forests covered by Sasa, and one bamboo forest) in eastern Japan in 2013. Comparing the results of 137Cs activity concentrations between roots and soil matrix taken at the same soil layer, roots at the surface (0-5 cm) layer often showed lower values than the soil matrix. However, roots deeper than 5 cm had higher activity concentrations than the soil matrix, conversely. The 137Cs inventories ratio of roots to soil matrix are about 1% at the 0-5 and 5-10 cm soil layer, and about 2% at the soil layers deeper than 10 cm. These results suggest that decomposition of root litter little affect the short-term vertical migration of 137Cs in the forest soil. However, it indicates that continuous production and mortality of roots with relatively high 137Cs activity concentrations have an important role for changing the vertical distribution of 137Cs on time scale of decades, particularly at deeper soil layers.
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Affiliation(s)
- Wataru Sakashita
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan; Department of Forest Soils, FFPRI, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan.
| | - Satoru Miura
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Akio Akama
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Shinta Ohashi
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan; Department of Wood Properties and Processing, FFPRI, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Shigeto Ikeda
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan; Department of Forest Soils, FFPRI, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Tomoyuki Saitoh
- Tohoku Research Center, FFPRI, 92-25 Nabeyashiki, Shimokuriyagawa, Morioka, Iwate, 020-0123, Japan
| | - Masabumi Komatsu
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan; Department of Mushroom Science and Forest Microbiology, FFPRI, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Yoshiki Shinomiya
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute (FFPRI), 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan; Department of Forest Soils, FFPRI, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Shinji Kaneko
- Kansai Research Center, FFPRI, 68 Nagaikyutaroh, Momoyama, Fushimi, Kyoto, 612-0855, Japan
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11
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Manaka T, Ono K, Furusawa H, Ogo S, Miura S. Chemical sequential extraction of O horizon samples from Fukushima forests: Assessment for degradability and radiocesium retention capacity of organic matters. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 220-221:106306. [PMID: 32658642 DOI: 10.1016/j.jenvrad.2020.106306] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 05/08/2020] [Accepted: 05/08/2020] [Indexed: 06/11/2023]
Abstract
To investigate how radiocesium (137Cs) is retained in the O horizon via interactions with organic matter, we collected O horizon samples in Japanese cedar (Cryptomeria japonica) and konara oak (Quercus serrata) forest sites in Fukushima during the 8 years following the Fukushima Dai-ichi Nuclear Power Plant accident. To assess degradability and 137Cs retention capacity of organic matter, we conducted chemical sequential extraction with organic solvent and sulfuric acid, collecting the following fractions: organic solvent extractives (Fraction 1), acid-soluble carbohydrates (Fraction 3), and acid-insoluble residue (Fraction 4). In all samples, across sampling years and sites, 137Cs content in Fractions 1, 3, and 4, as a proportion of the total 137Cs content, was 0.0-23.6%, 18.4-42.9%, and 44.8-76.0%, respectively. Generally, 137Cs is considered to be electrostatically bound to organic matter and relatively mobile, making it easily extractable by sulfuric acid treatment. However, we observed a relatively high proportion of 137Cs in Fraction 4, suggesting strong retention of 137Cs and their immobility in the O horizon. Complex organic matter such as lignin or tannin may contribute this retention. We also noted that some part of 137Cs may be also retained by clay minerals in the O horizon. Although organic matter in Fractions 1 and 3 is considered to decompose faster than that in Fraction 4, over the observation period the 137Cs proportion and net rate of decrease in 137Cs content (in total and in each fraction) remained nearly constant. This result implies that decomposition of organic matter and the consequent release of bound 137Cs may be partly compensated by additional input of 137Cs from the canopy and 137Cs recycling by soil microorganisms. Our study highlights the potential role of organic matter in the O horizon as a temporary reservoir of 137Cs and a driver of the 137Cs cycle in forest ecosystems.
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Affiliation(s)
- Takuya Manaka
- Department of Forest Soils, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan.
| | - Kenji Ono
- Tohoku Research Center, Forestry and Forest Products Research Institute, 92-25 Nabeyashiki, Shimokuriyagawa, Morioka, Iwate, 020-0123, Japan
| | - Hitomi Furusawa
- Department of Forest Soils, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Sumika Ogo
- Department of Mushroom Science and Forest Microbiology, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
| | - Satoru Miura
- Center for Forest Restoration and Radioecology, Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki, 305-8687, Japan
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12
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Stabilization/Solidification of Strontium Using Magnesium Silicate Hydrate Cement. Processes (Basel) 2020. [DOI: 10.3390/pr8020163] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Magnesium silicate hydrate (M–S–H) cement, formed by reacting MgO, SiO2, and H2O, was used to encapsulate strontium (Sr) radionuclide. Samples were prepared using light-burned magnesium oxide and silica fume, with sodium hexametaphosphate added to the mix water as a dispersant. The performance of the materials formed was evaluated by leach testing and the microstructure of the samples was also characterized. The stabilizing/solidifying effect on Sr radionuclide in the MgO–SiO2–H2O system with low alkalinity is demonstrated in the study. The leaching rate in a standard 42-day test was 2.53 × 10−4 cm/d, and the cumulative 42-day leaching fraction was 0.06 cm. This meets the relevant national standard performance for leaching requirements. Sr2+ was effectively incorporated into the M–S–H hydration products and new phase formation resulted in low Sr leaching being observed.
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13
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Hashimoto S, Imamura N, Kaneko S, Komatsu M, Matsuura T, Nishina K, Ohashi S. New predictions of 137Cs dynamics in forests after the Fukushima nuclear accident. Sci Rep 2020; 10:29. [PMID: 31913315 PMCID: PMC6949301 DOI: 10.1038/s41598-019-56800-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 10/30/2019] [Indexed: 11/13/2022] Open
Abstract
Most of the area contaminated by the Fukushima Daiichi Nuclear Power Plant accident is covered by forest. In this paper, we updated model predictions of temporal changes in the 137Cs dynamics using the latest observation data and newly provided maps of the predicted 137Cs activity concentration for wood, which is the most commercially important part of the tree body. Overall, the previous prediction and latest observation data were in very good agreement. However, further validation revealed that the migration from the soil surface organic layer to the mineral soil was overestimated for evergreen needleleaf forests. The new prediction of the 137Cs inventory showed that although the 137Cs distribution within forests differed among forest types in the first 5 years, the difference diminished in the later phase. Besides, the prediction of the wood 137Cs activity concentrations reproduced the different trends of the 137Cs activity concentrations for cedar, oak, and pine trees. Our simulation suggests that the changes of the wood 137Cs activity concentration over time will slow down after 5–10 years. Although the model uncertainty should be considered and monitoring and model updating must continue, the study provides helpful information on the 137Cs dynamics within forest ecosystems and the changes in wood contamination.
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Affiliation(s)
- Shoji Hashimoto
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan. .,Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Naohiro Imamura
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Shinji Kaneko
- Kansai Research Center, Forestry and Forest Products Research Institute, Fushimi, Kyoto, 612-0855, Japan
| | - Masabumi Komatsu
- Department of Mushroom Science and Forest Microbiology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Toshiya Matsuura
- Department of Forest Management, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Kazuya Nishina
- Center for Regional Environmental Research, National Institute for Environmental Studies, Tsukuba, 305-8506, Japan
| | - Shinta Ohashi
- Department of Wood Properties and Processing, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
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14
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Takahashi J, Onda Y, Hihara D, Tamura K. Six-year monitoring of the vertical distribution of radiocesium in three forest soils after the Fukushima Dai-ichi Nuclear Power Plant accident. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 210:105811. [PMID: 30377022 DOI: 10.1016/j.jenvrad.2018.09.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 05/31/2018] [Accepted: 06/22/2018] [Indexed: 06/08/2023]
Abstract
After the Fukushima Dai-ichi Nuclear Power Plant accident on March 2011, several studies showed that the downward migration of 137Cs from litter to mineral soil is more rapid in forests in Fukushima than in forests affected by the Chernobyl accident. Therefore, the downward migration within mineral soil layers is more important for predicting long-term dynamics of 137Cs in forest ecosystems in Fukushima. In the present study, we monitored the detailed vertical distribution of 137Cs in litter and soil layers for 6 y (2011-2017) following the previous study (2011-2012), and found that temporal changes in those distributions were different among mixed forest (MF), mature cedar (MC) and young cedar (YC) forests. The 137Cs concentrations and inventories in the litter layer exponentially decreased with time for all sites, with more than 80-95% of the deposited 137Cs on the forest floor distributed in mineral soil layers by 2017. The percentage of 137Cs inventory in the litter layer to the total 137Cs inventory in litter and mineral soil layers was well fitted by a single exponential equation with decreasing rate of 0.22-0.44 y-1. The slower migration was observed in the YC site, probably because of higher initial interception of 137Cs fallout by dense canopy. As the downward migration from litter to mineral soil progressed, the 137Cs concentration in the first few cm of mineral soil surface gradually increased and became higher than the 137Cs concentration in the litter within 2-3 y of the accident. The 137Cs concentration in mineral soil layers exponentially decreased with depth throughout survey period, and an exponential equation fitted well. The relaxation depth of 137Cs concentration in mineral soil layers estimated by the exponential equation were constantly increasing in the MC and YC sites with 0.08 cm y-1. In contrast, there was no temporal increase in the relaxation depth in the MF site, indicating little migration to subsurface soil layer from not only litter layer but also surface soil layer. Further studies are necessary to identify the forests prone to the downward migration of 137Cs and its factors regarding both forest and soil characteristics.
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Affiliation(s)
- Junko Takahashi
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Japan.
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Japan
| | - Daichi Hihara
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan
| | - Kenji Tamura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Japan
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15
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Kurikami H, Sakuma K, Malins A, Sasaki Y, Niizato T. Numerical study of transport pathways of 137Cs from forests to freshwater fish living in mountain streams in Fukushima, Japan. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 208-209:106005. [PMID: 31279227 DOI: 10.1016/j.jenvrad.2019.106005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 06/21/2019] [Accepted: 06/28/2019] [Indexed: 06/09/2023]
Abstract
The accident at the Fukushima Dai-ichi Nuclear Power Plant in 2011 released a large quantity of radiocesium into the surrounding environment. Radiocesium concentrations in some freshwater fish caught in rivers in Fukushima Prefecture in October 2018 were still higher than the Japanese limit of 100 Bq kg-1 for general foodstuffs. To assess the uptake of 137Cs by freshwater fish living in mountain streams in Fukushima Prefecture, we developed a compartment model for the migration of 137Cs on the catchment scale from forests to river water. We modelled a generic forest catchment with Fukushima-like parameters to ascertain the importance of three export pathways of 137Cs from forests to river water for the uptake of 137Cs by freshwater fish. The pathways were direct litter fall into rivers, lateral inflow from the forest litter layer, and lateral transfer from the underlying forest soil. Simulation cases modelling only a single export pathway did not reproduce the actual trend of 137Cs concentrations in river water and freshwater fish in Fukushima Prefecture. Simulations allowing a combined effect of the three pathways reproduced the trends well. In the latter simulations, the decreasing trend of 137Cs in river water and freshwater fish was due to a combination of the decreasing trend in the forest leaves/needles and litter compartments, and the increasing trend in soil. The modelled 137Cs concentrations within the forest compartments were predicted to reach an equilibrium state at around ten years after the fallout due to the equilibration of 137Cs cycling in forests. The model suggests that long term 137Cs concentrations in freshwater fish in mountain streams will be controlled by the transfer of 137Cs to river water from forest organic soils.
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Affiliation(s)
- Hiroshi Kurikami
- Japan Atomic Energy Agency (JAEA), Sector of Fukushima Research and Development, 10-2 Fukasaku, Miharu-machi, Tamura-gun, Fukushima, 963-7700, Japan.
| | - Kazuyuki Sakuma
- Japan Atomic Energy Agency (JAEA), Sector of Fukushima Research and Development, 10-2 Fukasaku, Miharu-machi, Tamura-gun, Fukushima, 963-7700, Japan.
| | - Alex Malins
- Japan Atomic Energy Agency (JAEA), Center for Computational Science & e-Systems, University of Tokyo Kashiwanoha Campus Satellite, 178-4-4 Wakashiba, Kashiwa, Chiba, 277-0871, Japan.
| | - Yoshito Sasaki
- Japan Atomic Energy Agency (JAEA), Sector of Fukushima Research and Development, 10-2 Fukasaku, Miharu-machi, Tamura-gun, Fukushima, 963-7700, Japan.
| | - Tadafumi Niizato
- Japan Atomic Energy Agency (JAEA), Sector of Fukushima Research and Development, 10-2 Fukasaku, Miharu-machi, Tamura-gun, Fukushima, 963-7700, Japan.
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16
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Muto K, Atarashi-Andoh M, Matsunaga T, Koarashi J. Characterizing vertical migration of 137Cs in organic layer and mineral soil in Japanese forests: Four-year observation and model analysis. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 208-209:106040. [PMID: 31518883 DOI: 10.1016/j.jenvrad.2019.106040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 06/20/2019] [Accepted: 08/27/2019] [Indexed: 06/10/2023]
Abstract
Because of the Fukushima Dai-ichi Nuclear Power Plant accident, forest ecosystems in wide areas were contaminated with 137Cs. It is important to characterize the behavior of 137Cs after its deposition onto forest surface environments for evaluating and preventing long-term radiation risks. In the present study, 137Cs vertical distributions in the soil profile were observed repeatedly at five forest sites with different vegetation types for 4.4 years after the accident in 2011, and 137Cs migration in the organic layer and mineral soil was analyzed based on a comparison of models and observations. Cesium-137 migration from the organic layer to the underlying mineral soil was represented by a two-component exponential model. Cesium-137 migration from the organic layer was faster than that observed in European forests, suggesting that the mobility and bioavailability of 137Cs could be suppressed rapidly in Japanese forests. At all sites, 137Cs transfer in mineral soil could be reproduced by a simple diffusion equation model with continuous 137Cs supply from the organic layer. The diffusion coefficients of 137Cs in the mineral soil were estimated to be 0.042-0.55 cm2 y-1, which were roughly comparable with those of European forest soils affected by the Chernobyl Nuclear Power Plant accident. Model predictions using the determined model parameters indicated that 10 years after the accident, more than 70% of the deposited 137Cs will migrate to the mineral soil but only less than 10% of the total 137Cs inventory will penetrate deeper than 10 cm in the mineral soil across all sites. The results of the present study suggest that the 137Cs deposited onto Japanese forest ecosystems will be retained in the surface layers of mineral soil for a long time.
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Affiliation(s)
- Kotomi Muto
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Mariko Atarashi-Andoh
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Takeshi Matsunaga
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan
| | - Jun Koarashi
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki, 319-1195, Japan.
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17
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Taira Y, Inadomi Y, Hirajou S, Fukumoto Y, Orita M, Yamada Y, Takamura N. Eight years post-Fukushima: is forest decontamination still necessary? JOURNAL OF RADIATION RESEARCH 2019; 60:705-707. [PMID: 31271433 PMCID: PMC6806016 DOI: 10.1093/jrr/rrz047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Revised: 05/17/2019] [Indexed: 06/09/2023]
Affiliation(s)
- Yasuyuki Taira
- Department of Global Health, Medicine and Welfare, Atomic Bomb Disease Institute, Nagasaki University, 1-12-4 Sakamoto, Nagasaki city, Nagasaki, Japan
| | - Yudai Inadomi
- Department of Global Health, Medicine and Welfare, Atomic Bomb Disease Institute, Nagasaki University, 1-12-4 Sakamoto, Nagasaki city, Nagasaki, Japan
| | - Shota Hirajou
- Department of Global Health, Medicine and Welfare, Atomic Bomb Disease Institute, Nagasaki University, 1-12-4 Sakamoto, Nagasaki city, Nagasaki, Japan
| | - Yasuhiro Fukumoto
- Department of Global Health, Medicine and Welfare, Atomic Bomb Disease Institute, Nagasaki University, 1-12-4 Sakamoto, Nagasaki city, Nagasaki, Japan
| | - Makiko Orita
- Department of Global Health, Medicine and Welfare, Atomic Bomb Disease Institute, Nagasaki University, 1-12-4 Sakamoto, Nagasaki city, Nagasaki, Japan
| | - Yumiko Yamada
- Department of Global Health, Medicine and Welfare, Atomic Bomb Disease Institute, Nagasaki University, 1-12-4 Sakamoto, Nagasaki city, Nagasaki, Japan
| | - Noboru Takamura
- Department of Global Health, Medicine and Welfare, Atomic Bomb Disease Institute, Nagasaki University, 1-12-4 Sakamoto, Nagasaki city, Nagasaki, Japan
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18
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Nakagawa H. Habitat changes and population dynamics of fishes in a stream with forest floor degradation due to deer overconsumption in its catchment area. CONSERVATION SCIENCE AND PRACTICE 2019. [DOI: 10.1111/csp2.71] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Affiliation(s)
- Hikaru Nakagawa
- Field Science Education and Research CenterKyoto University Kyoto Japan
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19
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Itthipoonthanakorn T, Dann SE, Crout NMJ, Shaw G. Nuclear weapons fallout 137Cs in temperate and tropical pine forest soils, 50 years post-deposition. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 660:807-816. [PMID: 30743966 DOI: 10.1016/j.scitotenv.2019.01.073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/07/2019] [Accepted: 01/07/2019] [Indexed: 06/09/2023]
Abstract
Following nuclear releases to the environment, 137Cs (half-life 30 years) is a long-term contaminant of many ecosystems, including forests. We recently sampled soils under pine forests in temperate and tropical climates to test the hypothesis that migration of 137Cs, 50 years after nuclear weapons fallout, is coupled with organic matter (OM) accumulation in these soils. Depth profiles of 137Cs, naturally-occurring 210Pb and weapons-derived 241Am were measured. After 50 years, migration of 137Cs into the temperate and tropical soils is limited to half-depths of 7-8 cm and 2-3 cm, respectively. At both locations, most 137Cs is associated with OM that accumulated from the early to mid-1960s. Illite, which immobilises radiocaesium, was undetectable by X-ray diffraction in the layer of peak 137Cs accumulation in the temperate forest soil, but apparent in the zone of peak concentration in the tropical soil. Data indicate that long-term (50 year) fate of 137Cs in organic-rich, temperate forest soil is coupled with OM accumulation; fixation of 137Cs by illite is more important in the tropical forest soil where OM is rapidly decomposed. Models of long-term radiocaesium migration in forest soils should explicitly account for the role of OM, especially when considering forests under contrasting climatic regimes.
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Affiliation(s)
| | - S E Dann
- Department of Chemistry, Loughborough University, Loughborough LE11 3TU, UK
| | - N M J Crout
- School of Biosciences, University of Nottingham, Sutton Bonington LE12 5RD, UK
| | - G Shaw
- School of Biosciences, University of Nottingham, Sutton Bonington LE12 5RD, UK.
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20
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Saito R, Kabeya M, Nemoto Y, Oomachi H. Monitoring 137Cs concentrations in bird species occupying different ecological niches; game birds and raptors in Fukushima Prefecture. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2019; 197:67-73. [PMID: 30544020 DOI: 10.1016/j.jenvrad.2018.10.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 10/30/2018] [Accepted: 10/31/2018] [Indexed: 06/09/2023]
Abstract
This study was conducted to assess radiocesium accumulation in birds after the accident at Tokyo Electric Power Company's Fukushima Daiichi Nuclear Power Station in 2011, with a particular focus on 137Cs, which has a long physical half-life. Results of 137Cs monitoring in four game bird species including two pheasant species and two duck species (copper pheasant, green pheasant, spot-billed duck and mallard) were assessed in Fukushima Prefecture. We also obtained samples from rescued raptors that died during treatment or rehabilitation at the Wildlife Symbiosis Centre in Fukushima Prefecture because of severe injury. We measured the muscle concentrations of 137Cs in four of these raptor species (black kite, northern goshawk, peregrine falcon and ural owl). Comparison of the two pheasant species showed that the copper pheasants inhabiting forested areas had higher 137Cs concentrations in muscle (Bq/kg, fresh mass) than the green pheasants inhabiting mountainous areas near human habitation (i.e., Satoyama). No clear tendencies were observed in 137Cs concentration in muscle of copper pheasants over time, but a tendency to decrease was observed in green pheasants over time. The difference in tendencies between species may be attributable to differences in their food habits and its 137Cs concentration, and also differences in the situation of 137Cs accumulation in their habitat. No significant differences were observed in 137Cs concentration in muscle between the resident spot-billed duck and migratory mallard because of the comparatively short biological of effective half-life of radiocesium. Analysis of 137Cs concentration in muscle of raptor revealed that the concentration was similar to, or lower than, those of pheasants and ducks.
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Affiliation(s)
- Rie Saito
- Fukushima Prefectural Centre for Environmental Creation, 10-2 Fukasaku, Miharu, Fukushima, 963-7700, Japan.
| | - Masahiko Kabeya
- Wildlife Symbiosis Centre, 67 Nagakubo, Tamai, Ootama Village, Fukushima, 969-1302, Japan
| | - Yui Nemoto
- Fukushima Prefectural Centre for Environmental Creation, 10-2 Fukasaku, Miharu, Fukushima, 963-7700, Japan
| | - Hitoshi Oomachi
- Fukushima Prefectural Centre for Environmental Creation, 10-2 Fukasaku, Miharu, Fukushima, 963-7700, Japan
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21
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Low 137Cs retention capability of organic layers in Japanese forest ecosystems affected by the Fukushima nuclear accident. J Radioanal Nucl Chem 2019. [DOI: 10.1007/s10967-019-06435-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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22
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Ogo S, Yamanaka T, Akama K, Nagakura J, Yamaji K. Influence of Ectomycorrhizal Colonization on Cesium Uptake by Pinus densiflora Seedlings. MYCOBIOLOGY 2018; 46:388-395. [PMID: 30637147 PMCID: PMC6319452 DOI: 10.1080/12298093.2018.1538074] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 07/24/2018] [Accepted: 08/23/2018] [Indexed: 06/01/2023]
Abstract
Radionuclides were deposited at forest areas in eastern parts of Japan following the Fukushima Daiichi Nuclear Power Plant incident in March 2011. Ectomycorrhizal (EM) fungi have important effects on radiocaesium dynamics in forest ecosystems. We examined the effect of colonization by the EM fungus Astraeus hygrometricus on the uptake of cesium (Cs) and potassium (K) by Pinus densiflora seedlings. Pine seedlings exhibited enhanced growth after the EM formation due to the colonization by A. hygrometricus. Additionally, the shoot Cs concentration increased after the EM formation when Cs was not added to the medium. This suggests that A. hygrometricus might be able to solubilize Cs fixed to soil particles. Moreover, the shoot K concentration increased significantly after the EM formation when Cs was added. However, there were no significant differences in the root K concentration between EM and non-EM seedlings. These results suggest that different mechanisms control the transfer of Cs and K from the root to the shoot of pine seedlings.
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Affiliation(s)
- Sumika Ogo
- Forestry and Forest Products Research Institute, Tsukuba, Japan
| | | | - Keiko Akama
- Forestry and Forest Products Research Institute, Tsukuba, Japan
| | - Junko Nagakura
- Forestry and Forest Products Research Institute, Tsukuba, Japan
| | - Keiko Yamaji
- College of Agrobiological Resource Science, Tsukuba University, Tsukuba, Japan
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Takahashi J, Onda Y, Hihara D, Tamura K. Six-year monitoring of the vertical distribution of radiocesium in three forest soils after the Fukushima Dai-ichi Nuclear Power Plant accident. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 192:172-180. [PMID: 29982001 DOI: 10.1016/j.jenvrad.2018.06.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 05/31/2018] [Accepted: 06/22/2018] [Indexed: 05/22/2023]
Abstract
After the Fukushima Dai-ichi Nuclear Power Plant accident on March 2011, several studies showed that the downward migration of 137Cs from litter to mineral soil is more rapid in forests in Fukushima than in forests affected by the Chernobyl accident. Therefore, the downward migration within mineral soil layers is more important for predicting long-term dynamics of 137Cs in forest ecosystems in Fukushima. In the present study, we monitored the detailed vertical distribution of 137Cs in litter and soil layers for 6 y (2011-2017) following the previous study (2011-2012), and found that temporal changes in those distributions were different among mixed forest (MF), mature cedar (MC) and young cedar (YC) forests. The 137Cs concentrations and inventories in the litter layer exponentially decreased with time for all sites, with more than 80-95% of the deposited 137Cs on the forest floor distributed in mineral soil layers by 2017. The percentage of 137Cs inventory in the litter layer to the total 137Cs inventory in litter and mineral soil layers was well fitted by a single exponential equation with decreasing rate of 0.22-0.44 y-1. The slower migration was observed in the YC site, probably because of higher initial interception of 137Cs fallout by dense canopy. As the downward migration from litter to mineral soil progressed, the 137Cs concentration in the first few cm of mineral soil surface gradually increased and became higher than the 137Cs concentration in the litter within 2-3 y of the accident. The 137Cs concentration in mineral soil layers exponentially decreased with depth throughout survey period, and an exponential equation fitted well. The relaxation depth of 137Cs concentration in mineral soil layers estimated by the exponential equation were constantly increasing in the MC and YC sites with 0.08 cm y-1. In contrast, there was no temporal increase in the relaxation depth in the MF site, indicating little migration to subsurface soil layer from not only litter layer but also surface soil layer. Further studies are necessary to identify the forests prone to the downward migration of 137Cs and its factors regarding both forest and soil characteristics.
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Affiliation(s)
- Junko Takahashi
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Japan.
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Japan
| | - Daichi Hihara
- Graduate School of Life and Environmental Sciences, University of Tsukuba, Japan
| | - Kenji Tamura
- Faculty of Life and Environmental Sciences, University of Tsukuba, Japan
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Thiry Y, Albrecht A, Tanaka T. Development and assessment of a simple ecological model (TRIPS) for forests contaminated by radiocesium fallout. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 190-191:149-159. [PMID: 29793757 DOI: 10.1016/j.jenvrad.2018.05.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 02/26/2018] [Accepted: 05/07/2018] [Indexed: 06/08/2023]
Abstract
The management of vast forested zones contaminated by radiocesium (rCs) following the Chernobyl and Fukushima fallout is of great social and economic concern in affected areas and requires appropriate dynamic models as predictive or questioning tools. Generally, the existing radio-ecological models need less fragmented data and more ecological realism in their quantitative description of the rCs cycling processes. The model TRIPS ("Transfer of Radionuclide In Perennial vegetation Systems") developed in this study privileged an integrated approach which makes the best use of mass balance studies and available explicit experimental data for Scots pine stands. A main challenge was the differentiation and calibration of foliar absorption as well as root uptake in order to well represent the rCs biocycling. The general dynamics of rCs partitioning was simulated with a relatively good precision against an independent series of observed values. In our scenario the rCs biological cycling enters a steady-state about 15 years after the atmospheric deposits. At that time, the simulations showed an equivalent contribution of foliage and root uptake to the tree contamination. But the root uptake seems not sufficient to compensate the activity decline in the tree. The initial foliar uptake and subsequent internal transfers were confirmed to have a great possible impact on the phasing of tree contamination. An extra finding concerns the roots system acting as a buffer in the early period. The TRIPS model is particularly useful in cases where site-specific integrated datasets are available, but it could also be used with adequate caution to generic sites. This development paves the way for simplification or integration of new modules, as well as for a larger number of other applications for the Chernobyl or Fukushima forests once the appropriate data become available. According to the sensitivity analysis that involves in particular reliable estimates of net foliar uptake as well as root uptake not disconnected from rCs exchange reactions in soil.
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Affiliation(s)
- Yves Thiry
- Andra, Research and Development Division, 1-7 rue Jean-Monnet, 92298 Châtenay-Malabry cedex, France.
| | - Achim Albrecht
- Andra, Research and Development Division, 1-7 rue Jean-Monnet, 92298 Châtenay-Malabry cedex, France
| | - Taku Tanaka
- EDF R&D, LNHE, 6 quai Watier, 78400 Chatou, France
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25
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Nishina K, Hashimoto S, Imamura N, Ohashi S, Komatsu M, Kaneko S, Hayashi S. Calibration of forest 137Cs cycling model "FoRothCs" via approximate Bayesian computation based on 6-year observations from plantation forests in Fukushima. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 193-194:82-90. [PMID: 30218793 DOI: 10.1016/j.jenvrad.2018.09.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 08/10/2018] [Accepted: 09/04/2018] [Indexed: 06/08/2023]
Abstract
Predicting the environmental fate of 137Cs in forest ecosystems along with the concentrations of 137Cs in tree parts are important for the managements of radioactively contaminated forests. In this study, we calibrate the Forest RothC and Cs model (FoRothCs), a forest ecosystem 137Cs dynamics model, using observational data obtained over six years from four forest sites with different levels of 137Cs contamination from Fukushima Prefecture. To this end, we applied an approximate Bayesian computation (ABC) technique based on the observed 137Cs concentrations (Bq kg-1) of five compartments (leaf, branch, stem, litter, and soil) in a Japanese cedar plantation. The environmental decay (increment) constants of the five compartments were used as the summary statistics (i.e., the metric for model performance) to infer the five parameters related to 137Cs transfer processes in FoRothCs. The ABC technique successfully reconciled the model outputs with the observed trends in 137Cs concentrations at all sites during the study period. Furthermore, the estimated parameters are in agreement with the literature values (e.g., the root uptake rates of 137Cs). Our study demonstrates that model calibration with ABC based on the trends in 137Cs concentrations of multi compartments is useful for reducing the prediction uncertainty of 137Cs dynamics in forest ecosystems.
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Affiliation(s)
- Kazuya Nishina
- Center for Regional Environmental Research, National Institute for Environmental Studies, 305-8506, 16-2, Onogawa, Tsukuba, Ibaraki, Japan.
| | - Shoji Hashimoto
- Forestry and Forest Products Research Institute, 305-8687, 1, Matsunosato, Tsukuba, Ibaraki, Japan; The University of Tokyo, 113-8657, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, Japan
| | - Naohiro Imamura
- Forestry and Forest Products Research Institute, 305-8687, 1, Matsunosato, Tsukuba, Ibaraki, Japan
| | - Shinta Ohashi
- Forestry and Forest Products Research Institute, 305-8687, 1, Matsunosato, Tsukuba, Ibaraki, Japan
| | - Masabumi Komatsu
- Forestry and Forest Products Research Institute, 305-8687, 1, Matsunosato, Tsukuba, Ibaraki, Japan
| | - Shinji Kaneko
- Kansai Research Center, Forestry and Forest Products Research Institute, 612-0855, 68, Nagaikyutaro, Momoyama, Fushimi, Kyoto, Japan
| | - Seiji Hayashi
- Fukushima Branch, National Institute for Environmental Studies, 963-7700, 10-2, Fukasaku, Miharu, Fukushima, Japan
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26
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Kurita K, Yamaguchi M, Nagao Y, Suzui N, Yin YG, Yoshihara T, Kawachi N. Development of an Easy and Simple Method to Measure the Environmental Radioactivity in Trees with Efficient Personal Dosimeters. ACTA ACUST UNITED AC 2018. [DOI: 10.3769/radioisotopes.67.427] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Affiliation(s)
- Keisuke Kurita
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
| | - Mitsutaka Yamaguchi
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
| | - Yuto Nagao
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
| | - Nobuo Suzui
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
| | - Yong-Gen Yin
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
| | - Toshihiro Yoshihara
- Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI)
| | - Naoki Kawachi
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology
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27
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Nemoto Y, Saito R, Oomachi H. Seasonal variation of Cesium-137 concentration in Asian black bear (Ursus thibetanus) and wild boar (Sus scrofa) in Fukushima Prefecture, Japan. PLoS One 2018; 13:e0200797. [PMID: 30020989 PMCID: PMC6051634 DOI: 10.1371/journal.pone.0200797] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2017] [Accepted: 07/03/2018] [Indexed: 11/22/2022] Open
Abstract
To elucidate and reduce the risk of radionuclide contamination in wildlife caused by the Tokyo Electric Power Company Fukushima Dai-ichi Nuclear Power Station accident, it is important to understand radionuclide variations in the wild animal population. Here, we used environmental monitoring data and muscle samples collected from Asian black bear (Ursus thibetanus) and wild boar (Sus scrofa) from May 2011 to March 2016 to examine seasonal variation in radiocesium (137Cs) concentrations in muscle tissues (hereafter, muscle 137Cs) of these important game species in Fukushima Prefecture. We measured muscle 137Cs of bears and wild boars killed by hunters or in animal control culls. First, using a linear mixed model (LMM), we tested for a positive relationship between muscle 137Cs and 137Cs in the soil at the site of capture (hereafter, soil 137Cs) estimated from a soil 137Cs deposition map produced by the Japan Atomic Energy Agency. In the LMM, muscle 137Cs was positively related to estimated soil 137Cs, which corroborates the results of previous studies. The LMM regression coefficients differed between the two species, with wild boar muscle 137Cs being higher than that of bears sampled at the same locations. We then employed a generalized additive mixed model (GAMM) to estimate seasonal variation in the muscle 137Cs of the target species. GAMM showed that muscle 137Cs varied seasonally and that this seasonal variation also differed between the two species. In bears, muscle 137Cs decreased from spring to early autumn, before increasing in winter. Wild boar muscle 137Cs remained low during spring and summer and was high during autumn and early spring. These patterns are likely influenced by differences in diet, habitat use, and physiology between these two species.
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Affiliation(s)
- Yui Nemoto
- Research Department, Fukushima Prefectural Centre for Environmental Creation, Miharu Town, Fukushima, Japan
- * E-mail:
| | - Rie Saito
- Research Department, Fukushima Prefectural Centre for Environmental Creation, Miharu Town, Fukushima, Japan
| | - Hitoshi Oomachi
- Research Department, Fukushima Prefectural Centre for Environmental Creation, Miharu Town, Fukushima, Japan
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28
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Schaettle K, Ruiz Pestana L, Head-Gordon T, Lammers LN. A structural coarse-grained model for clays using simple iterative Boltzmann inversion. J Chem Phys 2018; 148:222809. [DOI: 10.1063/1.5011817] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Karl Schaettle
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
| | - Luis Ruiz Pestana
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Teresa Head-Gordon
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, California 94720, USA
- Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, USA
- Department of Bioengineering, University of California, Berkeley, Berkeley, California 94720, USA
| | - Laura Nielsen Lammers
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, California 94720, USA
- Earth and Environmental Science Area, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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29
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Gonze MA, Calmon P. Meta-analysis of radiocesium contamination data in Japanese forest trees over the period 2011-2013. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 601-602:301-316. [PMID: 28570967 DOI: 10.1016/j.scitotenv.2017.05.175] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 05/15/2017] [Accepted: 05/20/2017] [Indexed: 06/07/2023]
Abstract
The fate and dispersion of radiocesium in forests affected by the Fukushima atmospheric fallouts have been efficiently characterized by Japanese scientists thanks to monitoring surveys of radioactive contents in contaminated soil, water, and vegetation samples at numerous sites. In this paper, we carry out a meta-analysis of the field surveys conducted over the period 2011-2013 in evergreen coniferous and deciduous broadleaf forests of Fukushima or neighboring prefectures. The review focuses on contamination data acquired in tree vegetation - about 1500 spatio-temporal measurements of concentrations, inventories and depuration fluxes - with a particular interest for organs that were directly exposed to the atmospheric fallouts and subjected to depuration mechanisms (foliage, branches and outer bark). To reduce the spatial variability between the sites, radioactive data were normalized by the total deposit estimated at each site. Our analysis highlights the overall consistency of field observations despite the variety of experimental protocols, disparate sampling periods, differences in the forest stand characteristics and variability of the atmospheric deposition conditions. Assuming that the sites conformed to the same dynamics (within the range of residual variability), we then derive, discuss, and compare the mean representative evolutions of radiocesium contamination in the two categories of forest. Thanks to a simple mass balance approach, we finally demonstrate that: (i) about 90% of the radiocesium deposit was intercepted by evergreen coniferous vegetation, (ii) 80% of the deposit was gradually transferred to the forest floor in 3years, according to a well characterized depuration kinetics, and (iii) about 4% was readily absorbed by the foliage and translocated to internal organs (inner bark, stem wood and roots) at a rate of about 10-4d-1.
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Affiliation(s)
- M-A Gonze
- Institute of Radiation Protection and Nuclear Safety, CE Cadarache-Bat 153, BP3 - 13115 St-Paul-lez-Durance Cedex, France.
| | - P Calmon
- Institute of Radiation Protection and Nuclear Safety, CE Cadarache-Bat 153, BP3 - 13115 St-Paul-lez-Durance Cedex, France
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Komatsu M, Hirai K, Nagakura J, Noguchi K. Potassium fertilisation reduces radiocesium uptake by Japanese cypress seedlings grown in a stand contaminated by the Fukushima Daiichi nuclear accident. Sci Rep 2017; 7:15612. [PMID: 29142200 PMCID: PMC5688087 DOI: 10.1038/s41598-017-15401-w] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Accepted: 10/20/2017] [Indexed: 12/03/2022] Open
Abstract
We analysed suppressive effects of potassium (K) fertilisation on radiocesium (137Cs) uptake by hinoki cypress (Chamaecyparis obtusa) seedlings from soils contaminated after the Fukushima Daiichi Nuclear Power Plant accident. Three-year-old seedlings were planted in a clear-cut forest (ca. 4 ha) during June–July 2014, and potassium chloride fertiliser (83 kg K ha−1) was applied twice (August 2014 and April 2015). 137Cs concentrations in the needles in the fertilised plots were one-eighth of those in the control (unfertilised) plots at the end of the second growing season (October 2015). Our results clearly indicated that K fertilisation reduced radiocesium transfer from soil to planted cypress seedlings. A linear mixed model analysis revealed that 137Cs concentrations in the needles were significantly affected by 137Cs inventory in the soil (Bq m−2) adjacent to the sampled seedlings, exchangeable K concentrations in surface mineral soils (0–5 cm) and fertilisation. The exchangeable K concentrations in surface soils in October 2015 did not differ from those in August 2014 (before fertilisation) in the fertilised plots and in the control plots. These results suggested that the levels of exchangeable K would temporarily increase by fertilisation during the growing season, and radiocesium uptake by tree roots was suppressed.
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Affiliation(s)
- Masabumi Komatsu
- Department of Mushroom Science and Forest Microbiology, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan.
| | - Keizo Hirai
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Junko Nagakura
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan
| | - Kyotaro Noguchi
- Department of Forest Soils, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki, 305-8687, Japan.,Tohoku Research Center, Forestry and Forest Products Research Institute, Morioka, Iwate, 020-0123, Japan
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31
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Ayabe Y, Hijii N, Takenaka C. Effects of local-scale decontamination in a secondary forest contaminated after the Fukushima nuclear power plant accident. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2017; 228:344-353. [PMID: 28551564 DOI: 10.1016/j.envpol.2017.05.041] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 05/11/2017] [Accepted: 05/17/2017] [Indexed: 06/07/2023]
Abstract
We investigated whether local-scale decontamination (removal of the litter layer, superficial soil layer, and understory) in a secondary forest contaminated by the Fukushima nuclear power plant accident reduced 137Cs contamination of the soil and litter. We also measured 137Cs concentrations in plants and in the web-building spider Nephila clavata (Nephilidae: Arachnida), as an indicator species, to examine 137Cs contamination in arthropods. One month after decontamination, the total 137Cs contamination (soil + litter) was reduced by 20% (100 kBq·m-2) relative to that in an adjacent untreated (i.e., contaminated) area, which was however not statistically significant. Four months after decontamination, 137Cs in the decontaminated area had increased to a level similar to those in the untreated area, and the air radiation dose in the decontaminated area was about 2.1 μSv·h-1, significantly higher than that in the untreated area (1.9 μSv·h-1). This may have been attributed to a torrential rain event. Although no statistically significant reduction was observed, most spiders had a lower 137Cs contamination than that before the decontamination. This implied that the decontamination may have reduced 137Cs transfer from soil via litter to N. clavata through the detrital food chains, but may not have reduced the amount of 137Cs transfer through grazing food chains because the concentration of 137Cs in living tree leaves was not reduced by the decontamination. In autumn, about 2 kBq·m-2 of 137Cs was supplied from foliage to the ground by litterfall. The results suggested that removal of the litter and superficial soil layers in a contaminated forest may be ineffective. The present study suggests that the local-scale decontamination in a secondary forest had no effect on the reduction of 137Cs contamination in the treated area.
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Affiliation(s)
- Yoshiko Ayabe
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
| | - Naoki Hijii
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
| | - Chisato Takenaka
- Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya 464-8601, Japan.
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32
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Ogo S, Yamanaka T, Akama K, Ota Y, Tahara K, Nagakura J, Kinoshita A, Yamaji K. Growth and uptake of caesium, rubidium, and potassium by ectomycorrhizal and saprotrophic fungi grown on either ammonium or nitrate as the N source. Mycol Prog 2017. [DOI: 10.1007/s11557-017-1317-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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33
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Aoki D, Asai R, Tomioka R, Matsushita Y, Asakura H, Tabuchi M, Fukushima K. Translocation of 133Cs administered to Cryptomeria japonica wood. THE SCIENCE OF THE TOTAL ENVIRONMENT 2017; 584-585:88-95. [PMID: 28135617 DOI: 10.1016/j.scitotenv.2017.01.159] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 01/17/2017] [Accepted: 01/23/2017] [Indexed: 05/21/2023]
Abstract
To reveal the in planta behaviour of caesium (Cs), the stable isotope 133Cs was administered into 3-year-old Cryptomeria japonica seedlings by the application of 133CsCl aqueous solution to the bark surface. The administered 133Cs was quantified by ICP-MS measurements, which showed transportation of 133Cs in an ascending direction in the stem. Distribution of 133Cs was visualized using freeze-fixed C. japonica woody stem samples and cryo-time-of-flight secondary ion mass spectrometry/scanning electron microscopy (cryo-TOF-SIMS/SEM) analysis. Cryo-TOF-SIMS/SEM visualization suggested that 133Cs was rapidly transported radially by ray parenchyma cells followed by axial transportation by pith and axial parenchyma cells. Adsorption experiments using powdered C. japonica wood samples and X-ray absorption fine structure (XAFS) analysis suggested that 133Cs was in the hydrated state following its deposition into tracheid cell walls.
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Affiliation(s)
- Dan Aoki
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan.
| | - Ryutaro Asai
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Rie Tomioka
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Yasuyuki Matsushita
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
| | - Hiroyuki Asakura
- Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University, 1-30 Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, Japan; Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Kyotodaigaku Katsura, Nishikyo-ku, Kyoto 615-8510, Japan
| | - Masao Tabuchi
- Synchrotron Radiation Research Center, Nagoya University, Furo-Cho, Chikusa-Ku, Nagoya 464-8603, Japan
| | - Kazuhiko Fukushima
- Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601, Japan
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34
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Takada M, Yamada T, Takahara T, Endo S, Tanaka K, Kajimoto T, Okuda T. Temporal changes in vertical distribution of 137Cs in litter and soils in mixed deciduous forests in Fukushima, Japan. J NUCL SCI TECHNOL 2017. [DOI: 10.1080/00223131.2017.1287602] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Momo Takada
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Toshihiro Yamada
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Teruhiko Takahara
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Satoru Endo
- Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Kenichi Tanaka
- Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Tsuyoshi Kajimoto
- Graduate School of Engineering, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
| | - Toshinori Okuda
- Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima, Hiroshima, Japan
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35
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Ishii Y, Hayashi S, Takamura N. Radiocesium Transfer in Forest Insect Communities after the Fukushima Dai-ichi Nuclear Power Plant Accident. PLoS One 2017; 12:e0171133. [PMID: 28125745 PMCID: PMC5268780 DOI: 10.1371/journal.pone.0171133] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 01/16/2017] [Indexed: 11/18/2022] Open
Abstract
To understand radiocesium transfer in the forest insect food web, we investigated the activity concentrations of radiocesium in forest insects in the Fukushima and Ibaraki Prefectures approximately 1.5–2.5 years after the Fukushima Dai-ichi Nuclear Power Plant. We analyzed 34 species of insects sampled from 4 orders and 4 feeding functional groups (herbivore, carnivore, omnivore, and detritivore) from three sites in each prefecture. 137Cs activity concentrations were lowest in herbivorous species and were especially high in detritivorous and omnivorous species that feed on forest litter and fungi. Radiocesium activity concentrations in any given species reflected the degree of contamination of that species’ primary food sources since radiocesium activity concentrations were found to be the lowest in leaves and grass and the highest in litter, bark, and fungi. This study confirmed that litter and other highly contaminated forest components such as fungi, decaying wood, bryophytes, and lichens serve as sources of 137Cs transfer into the forest insect community.
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Affiliation(s)
- Yumiko Ishii
- Environmental Impact Assessment Section, Fukushima Branch, National Institute for Environmental Studies, Miharu Town, Tamura County, Fukushima, Japan
- * E-mail:
| | - Seiji Hayashi
- Environmental Impact Assessment Section, Fukushima Branch, National Institute for Environmental Studies, Miharu Town, Tamura County, Fukushima, Japan
| | - Noriko Takamura
- Center for Environmental Biology and Ecosystem Studies, National Institute for Environmental Studies, Tsukuba, Ibaraki, Japan
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36
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Koarashi J, Atarashi-Andoh M, Matsunaga T, Sanada Y. Forest type effects on the retention of radiocesium in organic layers of forest ecosystems affected by the Fukushima nuclear accident. Sci Rep 2016; 6:38591. [PMID: 27974832 PMCID: PMC5156898 DOI: 10.1038/srep38591] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Accepted: 11/08/2016] [Indexed: 11/16/2022] Open
Abstract
The Fukushima Daiichi nuclear power plant disaster caused serious radiocesium (137Cs) contamination of forest ecosystems over a wide area. Forest-floor organic layers play a key role in controlling the overall bioavailability of 137Cs in forest ecosystems; however, there is still an insufficient understanding of how forest types influence the retention capability of 137Cs in organic layers in Japanese forest ecosystems. Here we conducted plot-scale investigations on the retention of 137Cs in organic layers at two contrasting forest sites in Fukushima. In a deciduous broad-leaved forest, approximately 80% of the deposited 137Cs migrated to mineral soil located below the organic layers within two years after the accident, with an ecological half-life of approximately one year. Conversely, in an evergreen coniferous forest, more than half of the deposited 137Cs remained in the organic layers, with an ecological half-life of 2.1 years. The observed retention behavior can be well explained by the tree phenology and accumulation of 137Cs associated with litter materials with different degrees of degradation in the organic layers. Spatial and temporal patterns of gamma-ray dose rates depended on the retention capability. Our results demonstrate that enhanced radiation risks last longer in evergreen coniferous forests than in deciduous broad-leaved forests.
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Affiliation(s)
- Jun Koarashi
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan
| | - Mariko Atarashi-Andoh
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan
| | - Takeshi Matsunaga
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan
| | - Yukihisa Sanada
- Fukushima Environmental Safety Center, Japan Atomic Energy Agency, Fukushima 975-0036, Japan
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37
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Koarashi J, Nishimura S, Nakanishi T, Atarashi-Andoh M, Takeuchi E, Muto K. Post-deposition early-phase migration and retention behavior of radiocesium in a litter-mineral soil system in a Japanese deciduous forest affected by the Fukushima nuclear accident. CHEMOSPHERE 2016; 165:335-341. [PMID: 27664523 DOI: 10.1016/j.chemosphere.2016.09.043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 09/12/2016] [Accepted: 09/12/2016] [Indexed: 06/06/2023]
Abstract
The fate of radiocesium (137Cs) derived from the Fukushima nuclear accident and associated radiation risks are largely dependent on its migration and retention behavior in the litter-soil system of Japanese forest ecosystems. However, this behavior has not been well quantified. We established field lysimeters in a Japanese deciduous broad-leaved forest soon after the Fukushima nuclear accident to continuously monitor the downward transfer of 137Cs at three depths: the litter-mineral soil boundary and depths of 5 cm and 10 cm in the mineral soil. Observations were conducted at two sites within the forest from May 2011 to May 2015. Results revealed similar temporal and depth-wise variations in 137Cs downward fluxes for both sites. The 137Cs downward fluxes generally decreased year by year at all depths, indicating that 137Cs was rapidly leached from the forest-floor litter layer and was then immobilized in the upper (0-5 cm) mineral soil layer through its interaction with clay minerals. The 137Cs fluxes also showed seasonal variation, which was in accordance with variations in the throughfall and soil temperature at the sites. There was no detectable 137Cs flux at a depth of 10 cm in the mineral soil in the third and fourth years after the accident. The decreased inventory of mobile (or bioavailable) 137Cs observed during early stages after deposition indicates that the litter-soil system in the Japanese deciduous forest provides only a temporary source for 137Cs recycling in plants.
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Affiliation(s)
- Jun Koarashi
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan.
| | - Syusaku Nishimura
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan
| | - Takahiro Nakanishi
- Sector of Fukushima Research and Development, Japan Atomic Energy Agency, Fukushima 970-8026, Japan
| | - Mariko Atarashi-Andoh
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan
| | - Erina Takeuchi
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan
| | - Kotomi Muto
- Nuclear Science and Engineering Center, Japan Atomic Energy Agency, Ibaraki 319-1195, Japan
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38
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Laceby JP, Huon S, Onda Y, Vaury V, Evrard O. Do forests represent a long-term source of contaminated particulate matter in the Fukushima Prefecture? JOURNAL OF ENVIRONMENTAL MANAGEMENT 2016; 183:742-753. [PMID: 27647133 DOI: 10.1016/j.jenvman.2016.09.020] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Revised: 09/02/2016] [Accepted: 09/03/2016] [Indexed: 06/06/2023]
Abstract
The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident resulted in radiocesium fallout contaminating coastal catchments of the Fukushima Prefecture. As the decontamination effort progresses, the potential downstream migration of radiocesium contaminated particulate matter from forests, which cover over 65% of the most contaminated region, requires investigation. Carbon and nitrogen elemental concentrations and stable isotope ratios are thus used to model the relative contributions of forest, cultivated and subsoil sources to deposited particulate matter in three contaminated coastal catchments. Samples were taken from the main identified sources: cultivated (n = 28), forest (n = 46), and subsoils (n = 25). Deposited particulate matter (n = 82) was sampled during four fieldwork campaigns from November 2012 to November 2014. A distribution modelling approach quantified relative source contributions with multiple combinations of element parameters (carbon only, nitrogen only, and four parameters) for two particle size fractions (<63 μm and <2 mm). Although there was significant particle size enrichment for the particulate matter parameters, these differences only resulted in a 6% (SD 3%) mean difference in relative source contributions. Further, the three different modelling approaches only resulted in a 4% (SD 3%) difference between relative source contributions. For each particulate matter sample, six models (i.e. <63 μm and <2 mm from the three modelling approaches) were used to incorporate a broader definition of potential uncertainty into model results. Forest sources were modelled to contribute 17% (SD 10%) of particulate matter indicating they present a long term potential source of radiocesium contaminated material in fallout impacted catchments. Subsoils contributed 45% (SD 26%) of particulate matter and cultivated sources contributed 38% (SD 19%). The reservoir of radiocesium in forested landscapes in the Fukushima region represents a potential long-term source of particulate contaminated matter that will require diligent management for the foreseeable future.
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Affiliation(s)
- J Patrick Laceby
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL), Unité Mixte de Recherche 8212 (CEA/CNRS/UVSQ), Université Paris-Saclay, Centre de Recherche du CNRS - Bât, 12 - Avenue de la terrasse, 91 198 Gif-sur-Yvette, France.
| | - Sylvain Huon
- Sorbonne Universités, UPMC Univ Paris 06, Institut d'Ecologie et des Sciences de l'Environnement de Paris (iEES), Case 120, 4 Place Jussieu, 75252 Paris Cedex 05, France
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Veronique Vaury
- Sorbonne Universités, UPMC Univ Paris 06, Institut d'Ecologie et des Sciences de l'Environnement de Paris (iEES), Case 120, 4 Place Jussieu, 75252 Paris Cedex 05, France
| | - Olivier Evrard
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL), Unité Mixte de Recherche 8212 (CEA/CNRS/UVSQ), Université Paris-Saclay, Centre de Recherche du CNRS - Bât, 12 - Avenue de la terrasse, 91 198 Gif-sur-Yvette, France
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39
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Cresswell AJ, Kato H, Onda Y, Nanba K. Evaluation of forest decontamination using radiometric measurements. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 164:133-144. [PMID: 27458868 DOI: 10.1016/j.jenvrad.2016.07.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 07/05/2016] [Accepted: 07/18/2016] [Indexed: 06/06/2023]
Abstract
An experiment has been conducted to evaluate the additional dose reduction by clear felling contaminated forestry in Fukushima Prefecture, Japan, and using the timber to cover the areas with wood chips. A portable gamma spectrometry system, comprising a backpack containing a 3 × 3″ NaI(Tl) detector with digital spectrometer and GPS receiver, has been used to map dose rate and radionuclide activity concentrations before, after and at stages during this experiment. The data show the effect of the different stages of the experiment on dose rate at different locations around the site. The spectrometric data have allowed the assessment of the contributions of natural and anthropogenic radionuclides to the dose rate at different parts of the site before and after the experiment. This has clearly demonstrated the value of radiometric methods in evaluating remediation, and the effect of other environmental processes. The value of spectrometric methods which directly measure radionuclide concentrations has also been shown, especially through the identification of the contribution of natural and anthropogenic activity to the measured dose rate. The experiment has shown that clearing trees and applying wood chips can reduce dose rates by 10-15% beyond that achieved by just clearing the forest litter and natural redistribution of radiocaesium.
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Affiliation(s)
- Alan J Cresswell
- Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima 960-1296, Japan.
| | - Hiroaki Kato
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan
| | - Kenji Nanba
- Institute of Environmental Radioactivity, Fukushima University, 1 Kanayagawa, Fukushima 960-1296, Japan
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40
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Yoshihara T, Matsumura H, Hashida SN, Nakaya K. Radiocesium contamination in living and dead foliar parts of Japanese cedar during 2011-2015. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 164:291-299. [PMID: 27537824 DOI: 10.1016/j.jenvrad.2016.08.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 07/27/2016] [Accepted: 08/07/2016] [Indexed: 06/06/2023]
Abstract
Radiocesium (137Cs) activity concentrations, mainly derived from the Fukushima accident of March 2011, were measured in green foliar parts without separation by age (bulk green foliar parts; GL) and litterfall (LF) of Japanese cedar (Cryptomeria japonica) from 2011 to 2015. In all samples, 137Cs concentrations decreased exponentially over time, but were always higher in LF (7.36-0.58 Bq g-DW-1) than in GL (2.10-0.06 Bq g-DW-1). The difference in the decreasing rate between GL and LF would reflect a difference in the dominant factor of the decrease between living and dead tissues (i.e., internal translocation and weathering, respectively). Over this same timeframe, potassium (K) concentrations in both GL and LF experienced repetitive periodical changes within a certain range (0.38-3.0 mg g-DW-1 for LF and 2.08-4.77 mg g-DW-1 for GL, respectively). Thus, there was no specific correlation between 137Cs and K concentrations in LF and GL. However, analyses of the age classified green foliar parts (GL-S) and dead foliar parts still retained on trees (DL) could indicate another view. The annual changes in residual rates of both 137Cs and K concentrations in GL-S demonstrated very similar two-phase reductions (i.e., a faster reduction in each expansion year than in the following years) and an obvious linear correlation between each other. Radiocesium concentration in DL were always higher than in any part of GL-S sampled at the same timing, but K concentrations showed the reverse relation. It is probable that 137Cs is basically translocated from older parts to the developing parts (as long as the former are alive) via a seasonal nutritional flow of K; however, a part of 137Cs translocation would cease considerably earlier than the cessation of K translocation.
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Affiliation(s)
- Toshihiro Yoshihara
- Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194, Japan.
| | - Hideyuki Matsumura
- Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194, Japan
| | - Shin-Nosuke Hashida
- Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194, Japan
| | - Ko Nakaya
- Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), 1646 Abiko, Chiba 270-1194, Japan
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41
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Evrard O, Laceby JP, Onda Y, Wakiyama Y, Jaegler H, Lefèvre I. Quantifying the dilution of the radiocesium contamination in Fukushima coastal river sediment (2011-2015). Sci Rep 2016; 6:34828. [PMID: 27694832 PMCID: PMC5046143 DOI: 10.1038/srep34828] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2016] [Accepted: 09/21/2016] [Indexed: 11/13/2022] Open
Abstract
Fallout from the Fukushima Dai-ichi nuclear power plant accident resulted in a 3000-km2 radioactive contamination plume. Here, we model the progressive dilution of the radiocesium contamination in 327 sediment samples from two neighboring catchments with different timing of soil decontamination. Overall, we demonstrate that there has been a ~90% decrease of the contribution of upstream contaminated soils to sediment transiting the coastal plains between 2012 (median – M – contribution of 73%, mean absolute deviation – MAD – of 27%) and 2015 (M 9%, MAD 6%). The occurrence of typhoons and the progress of decontamination in different tributaries of the Niida River resulted in temporary increases in local contamination. However, the much lower contribution of upstream contaminated soils to coastal plain sediment in November 2015 demonstrates that the source of the easily erodible, contaminated material has potentially been removed by decontamination, diluted by subsoils, or eroded and transported to the Pacific Ocean.
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Affiliation(s)
- Olivier Evrard
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL), Unité Mixte de Recherche 8212 (CEA/CNRS/UVSQ), Université Paris-Saclay, Gif-sur-Yvette (France)
| | - J Patrick Laceby
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL), Unité Mixte de Recherche 8212 (CEA/CNRS/UVSQ), Université Paris-Saclay, Gif-sur-Yvette (France)
| | - Yuichi Onda
- Center for Research in Isotopes and Environmental Dynamics (CRIED), University of Tsukuba, Tsukuba (Japan)
| | - Yoshifumi Wakiyama
- Institute of Environmental Radioactivity (IER), University of Fukushima, Fukushima (Japan)
| | - Hugo Jaegler
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL), Unité Mixte de Recherche 8212 (CEA/CNRS/UVSQ), Université Paris-Saclay, Gif-sur-Yvette (France)
| | - Irène Lefèvre
- Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL), Unité Mixte de Recherche 8212 (CEA/CNRS/UVSQ), Université Paris-Saclay, Gif-sur-Yvette (France)
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42
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Hashida SN, Yoshihara T. Disparate radiocesium leaching from two woody species by acceleration of litter decomposition using microbial inoculation. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 162-163:319-327. [PMID: 27323212 DOI: 10.1016/j.jenvrad.2016.06.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Revised: 06/10/2016] [Accepted: 06/12/2016] [Indexed: 06/06/2023]
Abstract
Studies focusing on the migration of radionuclides in the forest floor have demonstrated that the ecological half-life of radiocesium on organic layer containing the debris of plant litter with various fungi and microorganisms is shorter than that in the deeper soil zone, suggesting that the litter decomposition affects radiocesium mobilization. Here, we showed the involvement of lignin, one of the major cell wall components of plant litter, in the fate of contaminated radiocesium during the process of fungal litter decomposition. In this study, litter decomposition of two different woody species, broadleaf deciduous Japanese cherry consisted of hardwood lignin and coniferous evergreen Japanese cedar with softwood lignin, were accelerated by in vitro fungal inoculation. In vitro inoculation exhibited 1.93- to 2.59-times faster decomposition than field experiment. Then, the cherry litter lost approximately 25% of initially contaminated radiocesium within 1 month of in vitro decomposition, whereas the cedar litter kept initial level at least for 6 month. The retention of radiocesium correlated with thioglycolate lignin content in cedar litter but not in cherry litter. Consequently, the behavior of radiocesium contaminated in litter fall may vary depending on the contamination pathway or the manner of nutrient mobilization at the stage of abscission between evergreen and deciduous trees.
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Affiliation(s)
- Shin-Nosuke Hashida
- Plant Molecular Biology, Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), Abiko 1646, Abiko-shi, Chiba, Japan.
| | - Toshihiro Yoshihara
- Plant Molecular Biology, Laboratory of Environmental Science, Central Research Institute of Electric Power Industry (CRIEPI), Abiko 1646, Abiko-shi, Chiba, Japan
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43
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Vandenhove H, Turcanu C. Agricultural land management options after the Chernobyl and Fukushima accidents: The articulation of science, technology, and society. INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT 2016; 12:662-666. [PMID: 27640412 DOI: 10.1002/ieam.1826] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Revised: 07/11/2016] [Accepted: 07/22/2016] [Indexed: 06/06/2023]
Abstract
The options adopted for recovery of agricultural land after the Chernobyl and Fukushima accidents are compared by examining their technical and socio-economic aspects. The analysis highlights commonalities such as the implementation of tillage and other types of countermeasures and differences in approach, such as preferences for topsoil removal in Fukushima and the application of K fertilizers in Chernobyl. This analysis shows that the recovery approach needs to be context-specific to best suit the physical, social, and political environment. The complex nature of the decision problem calls for a formal process for engaging stakeholders and the development of adequate decision support tools. Integr Environ Assess Manag 2016;12:662-666. © 2016 SETAC.
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Affiliation(s)
- Hildegarde Vandenhove
- Environment Health and Safety, Belgian Nuclear Research Centre SCK•CEN, Mol, Belgium.
| | - Catrinel Turcanu
- Nuclear Science and Technology Studies, Belgian Nuclear Research Centre SCK•CEN, Mol, Belgium
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44
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Takada M, Yamada T, Takahara T, Okuda T. Spatial variation in the (137)Cs inventory in soils in a mixed deciduous forest in Fukushima, Japan. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 161:35-41. [PMID: 27173786 DOI: 10.1016/j.jenvrad.2016.04.033] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Revised: 04/22/2016] [Accepted: 04/25/2016] [Indexed: 06/05/2023]
Abstract
The spatial variation of the radiocesium inventory in forest soil was studied c.a. 44 km northwest of the Fukushima Daiichi Nuclear Power Plant, Japan. This study focuses on the effects of canopy interception and downward transfer from the forest canopy to the forest floor via stemflow and throughfall. We established a study plot (400 m(2)) in the canopy layer of a secondary mixed deciduous forest dominated by Japanese oak (Quercus crispula) and Japanese fir (Abies firma), in August and November 2014. Soil was sampled from 0 to 5 cm depth and (137)Cs was measured under the canopy using a 2-m grid and also at the tree trunk bases. We divided the study plot into the five different types of subplot according to the canopy projection areas and the tree species for the analysis. The geometric mean and coefficient of variation of the (137)Cs inventory were 202 kBq m(-2) and 0.11 (0.52 in the arithmetic coefficient of variation), respectively. Within the forest, the variation in the (137)Cs inventory under trees was larger than in crown gap areas. The large spatial variation may be attributed to canopy interception of the initial deposition and downward transfer of radiocesium via stemflow and throughfall.
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Affiliation(s)
- Momo Takada
- Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, 739-8521, Japan.
| | - Toshihiro Yamada
- Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, 739-8521, Japan
| | - Teruhiko Takahara
- Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, 739-8521, Japan; Faculty of Life and Environmental Science, Shimane University, 1060 Nishikawatsu, Matsue, Shimane, 690-8504, Japan
| | - Toshinori Okuda
- Graduate School of Integrated Arts and Sciences, Hiroshima University, 1-7-1 Kagamiyama, Higashi-Hiroshima, 739-8521, Japan
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45
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Niizato T, Abe H, Mitachi K, Sasaki Y, Ishii Y, Watanabe T. Input and output budgets of radiocesium concerning the forest floor in the mountain forest of Fukushima released from the TEPCO's Fukushima Dai-ichi nuclear power plant accident. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 161:11-21. [PMID: 27131868 DOI: 10.1016/j.jenvrad.2016.04.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 04/14/2016] [Accepted: 04/16/2016] [Indexed: 06/05/2023]
Abstract
Estimations of radiocesium input and output concerning the forest floor within a mountain forest region have been conducted in the north and central part of the Abukuma Mountains of Fukushima, northeast Japan, after a 2-3 year period following the TEPCO Fukushima Dai-ichi nuclear power plant accident. The radiocesium input and output associated with surface washoff, throughfall, stemflow, and litterfall processes at experimental plots installed on the forest floor of evergreen Japanese cedars and deciduous Konara oaks have been monitored. Despite the high output potential in the mountainous forest of Fukushima, the results at both monitoring locations show the radiocesium input to be 4-50 times higher than the output during the summer monsoon in Fukushima. These results indicate that the radiocesium tends to be preserved in the forest ecosystem due to extremely low output ratios (0.05%-0.19%). Thus, the associated fluxes throughout the circulation process are key issues for the projecting the environmental fate of the radiocesium levels, along with the subsequent reconstruction of life emphasized within the setting.
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Affiliation(s)
- Tadafumi Niizato
- Fukushima Environmental Safety Center, Japan Atomic Energy Agency, Fukushima 963-7700, Japan.
| | - Hironobu Abe
- Fukushima Environmental Safety Center, Japan Atomic Energy Agency, Fukushima 963-7700, Japan
| | - Katsuaki Mitachi
- Fukushima Environmental Safety Center, Japan Atomic Energy Agency, Fukushima 963-7700, Japan
| | - Yoshito Sasaki
- Fukushima Environmental Safety Center, Japan Atomic Energy Agency, Fukushima 963-7700, Japan
| | - Yasuo Ishii
- Fukushima Environmental Safety Center, Japan Atomic Energy Agency, Fukushima 963-7700, Japan
| | - Takayoshi Watanabe
- Fukushima Environmental Safety Center, Japan Atomic Energy Agency, Fukushima 963-7700, Japan
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46
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Komatsu M, Kaneko S, Ohashi S, Kuroda K, Sano T, Ikeda S, Saito S, Kiyono Y, Tonosaki M, Miura S, Akama A, Kajimoto T, Takahashi M. Characteristics of initial deposition and behavior of radiocesium in forest ecosystems of different locations and species affected by the Fukushima Daiichi Nuclear Power Plant accident. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 161:2-10. [PMID: 26432062 DOI: 10.1016/j.jenvrad.2015.09.016] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 08/15/2015] [Accepted: 09/15/2015] [Indexed: 06/05/2023]
Abstract
After the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident, information about stand-level spatial patterns of radiocesium initially deposited in the surrounding forests was essential for predicting the future dynamics of radiocesium and suggesting a management plan for contaminated forests. In the first summer (approximately 6 months after the accident), we separately estimated the amounts of radiocesium ((134)Cs and (137)Cs; Bq m(-2)) in the major components (trees, organic layers, and soils) in forests of three sites with different contamination levels. For a Japanese cedar (Cryptomeria japonica) forest studied at each of the three sites, the radiocesium concentration greatly differed among the components, with the needle and organic layer having the highest concentrations. For these cedar forests, the proportion of the (137)Cs stock in the aboveground tree biomass varied from 22% to 44% of the total (137)Cs stock; it was 44% in highly contaminated sites (7.0 × 10(5) Bq m(-2)) but reduced to 22% in less contaminated sites (1.1 × 10(4) Bq m(-2)). In the intermediate contaminated site (5.0-5.8 × 10(4) Bq m(-2)), 34% of radiocesium was observed in the aboveground tree biomass of the Japanese cedar stand. However, this proportion was considerably smaller (18-19%) in the nearby mixed forests of the Japanese red pine (Pinus densiflora) and deciduous broad-leaved trees. Non-negligible amounts of (134)Cs and (137)Cs were detected in both the sapwood and heartwood of all the studied tree species. This finding suggested that the uptake or translocation of radiocesium had already started within 6 months after the accident. The belowground compartments were mostly present in the organic layer and the uppermost (0-5 cm deep) mineral soil layer at all the study sites. We discussed the initial transfer process of radiocesium deposited in the forest and inferred that the type of initial deposition (i.e., dry versus wet radiocesium deposition), the amount of rainfall after the accident, and the leaf biomass by the tree species may influence differences in the spatial pattern of radiocesium by study plots. The results of the present study and further studies of the spatial pattern of radiocesium are important for modeling future radiocesium distribution in contaminated forest ecosystems.
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Affiliation(s)
- Masabumi Komatsu
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan.
| | - Shinji Kaneko
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Shinta Ohashi
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Katsushi Kuroda
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Tetsuya Sano
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan; Department of Environment and Energy, Tohoku Institute of Technology, 35-1 Yagiyamakasumi-cho, Taihaku-ku, Sendai, Miyagi 982-8577, Japan
| | - Shigeto Ikeda
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Satoshi Saito
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Yoshiyuki Kiyono
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Mario Tonosaki
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan; Shikoku Research Center, Forestry and Forest Products Research Institute, 2-915 Asakuranishimachi, Kochi, Kochi 780-8077, Japan
| | - Satoru Miura
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan; Laboratory of Radioplant Physiology, the University of Tokyo, 1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Akio Akama
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Takuya Kajimoto
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
| | - Masamichi Takahashi
- Forestry and Forest Products Research Institute, 1 Matsunosato, Tsukuba, Ibaraki 305-8687, Japan
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Ogawa H, Hirano Y, Igei S, Yokota K, Arai S, Ito H, Kumata A, Yoshida H. Changes in the distribution of radiocesium in the wood of Japanese cedar trees from 2011 to 2013. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 161:51-57. [PMID: 26774216 DOI: 10.1016/j.jenvrad.2015.12.021] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Revised: 12/24/2015] [Accepted: 12/24/2015] [Indexed: 06/05/2023]
Abstract
The changes in the distribution of (137)Cs in the wood of Japanese cedar (Cryptomeria japonica) trunks within three years after the Fukushima Dai-ichi Nuclear Power Plant (FDNP) accident in 2011 were investigated. Thirteen trees were felled to collect samples at 6 forests in 2 regions of the Fukushima prefecture. The radial distribution of (137)Cs in the wood was measured at different heights. Profiles of (137)Cs distribution in the wood changed considerably from 2011 to 2013, and the process of (137)Cs distribution change in the wood was clarified. From 2011 to 2012, the active transportation from sapwood to heartwood and the radial diffusion in heartwood proceeded quickly, and the radial (137)Cs distribution differed according to the vertical positon of trees. From 2012 to 2013, the vertical diffusion of (137)Cs from the treetop to the ground, probably caused by the gradient of (137)Cs concentration in the trunk, was observed. Eventually, the radial (137)Cs distributions were nearly identical at any vertical positions in 2013. Our results suggested that the active transportation from sapwood to heartwood and the vertical and radial diffusion in heartwood proceeded according to the vertical position of the tree and (137)Cs distribution in the wood approached the equilibrium state within three years after the accident.
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Affiliation(s)
- Hideki Ogawa
- Graduate School of Urban Environmental Science, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo 192-0397, Japan; Fukushima Prefectural Forestry Research Centre, Nishi-Shimasaka, Asaka, Koriyama, Fukushima 963-0112, Japan.
| | - Yurika Hirano
- Graduate School of Urban Environmental Science, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
| | - Shigemitsu Igei
- Graduate School of Urban Environmental Science, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
| | - Kahori Yokota
- Graduate School of Urban Environmental Science, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
| | - Shio Arai
- Graduate School of Urban Environmental Science, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
| | - Hirohisa Ito
- Fukushima Prefectural Forestry Research Centre, Nishi-Shimasaka, Asaka, Koriyama, Fukushima 963-0112, Japan
| | - Atsushi Kumata
- Fukushima Prefectural Forestry Research Centre, Nishi-Shimasaka, Asaka, Koriyama, Fukushima 963-0112, Japan
| | - Hirohisa Yoshida
- Graduate School of Urban Environmental Science, Tokyo Metropolitan University, Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
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48
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Thiry Y, Garcia-Sanchez L, Hurtevent P. Experimental quantification of radiocesium recycling in a coniferous tree after aerial contamination: Field loss dynamics, translocation and final partitioning. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 161:42-50. [PMID: 26774824 DOI: 10.1016/j.jenvrad.2015.12.017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Revised: 12/18/2015] [Accepted: 12/19/2015] [Indexed: 06/05/2023]
Abstract
After foliar interception of radioactive atmospheric fallout by forest trees, the short-term recycling dynamics of radiocesium from the tree to the soil as well as within the tree is a primary area of uncertainty in the modeling of the overall cycle. The partitioning of radiocesium transfers in a spruce tree exposed to aerial deposits was investigated during one growth season to reveal the dynamics and significance of underlying processes. The rate of radiocesium loss resulting from foliage leaching (wash-off) was shown to have a functional dependence on the frequency of rainy episodes in a first early stage (weathering 60% of initial contamination during 70 days) and on the amount of precipitation in a second stage (weathering 10% of initial deposits during the following 80 days). A classical single exponential decay model with offset and continuous time as predictor lead to a removal half-life t1/2 of intercepted radiocesium of 25 days. During the growth season, the similar pattern of the internal (134)Cs content in new shoots and initially contaminated foliage confirmed that radiocesium was readily absorbed from needle surfaces and efficiently translocated to growing organs. In the crown, a pool of non-leachable (134)Cs (15-30%) was associated with the abiotic layer covering the twigs and needle surfaces. At the end of the growth season, 30% of the initial deposits were relocated to different tree parts, including organs like stemwood (5%) and roots (6%) not directly exposed to deposition. At the scale of the tree, 84% of the residual activity was assimilated by living tissues which corresponds to a foliar absorption rate coefficient of 0.25 year(-1) for modeling purposes. According to the significant amount of radiocesium which can be incorporated in tree through foliar uptake, our results support the hypothesis that further internal transfers could supply the tree internal cycle of radiocesium extensively, and possibly mask the contribution of root uptake for a long time.
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Affiliation(s)
- Y Thiry
- National Radioactive Waste Management Agency (Andra), Scientific Division, 1-7, rue Jean Monnet, 92298 Châtenay-Malabry Cedex, France.
| | - L Garcia-Sanchez
- French Institute for Radiological Protection and Nuclear Safety (IRSN), PRP-ENV/SERIS/L2BT, CE Cadarache bt 183, BP 3, 13115 Saint-Paul-lez-Durance, France.
| | - P Hurtevent
- French Institute for Radiological Protection and Nuclear Safety (IRSN), PRP-ENV/SERIS/L2BT, CE Cadarache bt 183, BP 3, 13115 Saint-Paul-lez-Durance, France.
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49
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Vertical distributions of global fallout 137Cs and 14C in a Japanese forest soil profile and their implications for the fate and migration processes of Fukushima-derived 137Cs. J Radioanal Nucl Chem 2016. [DOI: 10.1007/s10967-016-4938-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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50
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Ota M, Nagai H, Koarashi J. Modeling dynamics of (137)Cs in forest surface environments: Application to a contaminated forest site near Fukushima and assessment of potential impacts of soil organic matter interactions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 551-552:590-604. [PMID: 26897402 DOI: 10.1016/j.scitotenv.2016.02.068] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/09/2016] [Accepted: 02/09/2016] [Indexed: 06/05/2023]
Abstract
A process-based model for (137)Cs transfer in forest surface environments was developed to assess the dynamic behavior of Fukushima-derived (137)Cs in a Japanese forest. The model simulation successfully reproduced the observed data from 3year migration of (137)Cs in the organic and mineral soil layers at a contaminated forest near Fukushima. The migration of (137)Cs from the organic layer to the mineral soil was explained by the direct deposition pattern on the forest floor and the turnover of litter materials in the organic layer under certain ecological conditions. Long-term predictions indicated that more than 90% of the deposited (137)Cs would remain within the top 5cm of the soil for up to 30years after the accident, suggesting that the forest acts as an effective long-term reservoir of (137)Cs with limited transfer via the groundwater pathway. The model was also used to explore the potential impacts of soil organic matter (SOM) interactions on the mobility and bioavailability of (137)Cs in the soil-plant system. The simulation results for hypothetical organic soils with modified parameters of (137)Cs turnover revealed that the SOM-induced reduction of (137)Cs adsorption elevates the fraction of dissolved (137)Cs in the soil solution, thereby increasing the soil-to-plant transfer of (137)Cs without substantially altering the fractional distribution of (137)Cs in the soil. Slower fixation of (137)Cs on the flayed edge site of clay minerals and enhanced mobilization of the clay-fixed (137)Cs in organic-rich soils also appeared to elevate the soil-to-plant transfer of (137)Cs by increasing the fraction of the soil-adsorbed (exchangeable) (137)Cs. A substantial proportion (approximate 30%-60%) of (137)Cs in these organic-rich soils was transferred to layers deeper than 5cm decades later. These results suggested that SOM influences the behavior of (137)Cs in forests over a prolonged period through alterations of adsorption and fixation in the soil.
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Affiliation(s)
- Masakazu Ota
- Research Group for Environmental Science, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan.
| | - Haruyasu Nagai
- Research Group for Environmental Science, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
| | - Jun Koarashi
- Research Group for Environmental Science, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195, Japan
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